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<h1>polyfill.js</h1>
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<h2 id="json">JSON</h2>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-comment">/*!
* JSON Parser (Public Domain)
* by Douglas Crockford
* http://javascript.crockford.com/
*/</span></pre></div></div>
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<p>Create a json object only if one does not already exist. We create the
methods in a closure to avoid creating global variables.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">var</span> json = {};
(<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">()</span> </span>{
<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> <span class="hljs-built_in">window</span>.JSON === <span class="hljs-string">"object"</span> && <span class="hljs-keyword">typeof</span> <span class="hljs-built_in">window</span>.JSON.parse === <span class="hljs-string">"function"</span>) {
json = <span class="hljs-built_in">window</span>.JSON;
<span class="hljs-keyword">return</span>;
}
<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">f</span> <span class="hljs-params">(n)</span> </span>{</pre></div></div>
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<p>Format integers to have at least two digits.</p>
</div>
<div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> n < <span class="hljs-number">10</span> ? <span class="hljs-string">"0"</span> + n : n;
}
<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> <span class="hljs-built_in">Date</span>.prototype.tojson !== <span class="hljs-string">"function"</span>) {
<span class="hljs-built_in">Date</span>.prototype.tojson = <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">()</span> </span>{
<span class="hljs-keyword">return</span> <span class="hljs-built_in">isFinite</span>(<span class="hljs-keyword">this</span>.valueOf()) ?
<span class="hljs-keyword">this</span>.getUTCFullYear() + <span class="hljs-string">"-"</span> +
f(<span class="hljs-keyword">this</span>.getUTCMonth() + <span class="hljs-number">1</span>) + <span class="hljs-string">"-"</span> +
f(<span class="hljs-keyword">this</span>.getUTCDate()) + <span class="hljs-string">"T"</span> +
f(<span class="hljs-keyword">this</span>.getUTCHours()) + <span class="hljs-string">":"</span> +
f(<span class="hljs-keyword">this</span>.getUTCMinutes()) + <span class="hljs-string">":"</span> +
f(<span class="hljs-keyword">this</span>.getUTCSeconds()) + <span class="hljs-string">"Z"</span>
: <span class="hljs-literal">null</span>;
};
<span class="hljs-built_in">String</span>.prototype.tojson =
<span class="hljs-built_in">Number</span>.prototype.tojson =
<span class="hljs-built_in">Boolean</span>.prototype.tojson = <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">()</span> </span>{
<span class="hljs-keyword">return</span> <span class="hljs-keyword">this</span>.valueOf();
};
}
<span class="hljs-keyword">var</span> cx = <span class="hljs-regexp">/[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g</span>,
escapable = <span class="hljs-regexp">/[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g</span>,
gap,
indent,
meta = { <span class="hljs-comment">// table of character substitutions</span>
<span class="hljs-string">"\b"</span>: <span class="hljs-string">"\\b"</span>,
<span class="hljs-string">"\t"</span>: <span class="hljs-string">"\\t"</span>,
<span class="hljs-string">"\n"</span>: <span class="hljs-string">"\\n"</span>,
<span class="hljs-string">"\f"</span>: <span class="hljs-string">"\\f"</span>,
<span class="hljs-string">"\r"</span>: <span class="hljs-string">"\\r"</span>,
<span class="hljs-string">"\""</span> : <span class="hljs-string">"\\\""</span>,
<span class="hljs-string">"\\"</span>: <span class="hljs-string">"\\\\"</span>
},
rep;
<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">quote</span><span class="hljs-params">(string)</span> </span>{</pre></div></div>
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<p>If the string contains no control characters, no quote characters, and no
backslash characters, then we can safely slap some quotes around it.
Otherwise we must also replace the offending characters with safe escape
sequences.</p>
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<div class="content"><div class='highlight'><pre>
escapable.lastIndex = <span class="hljs-number">0</span>;
<span class="hljs-keyword">return</span> escapable.test(string) ? <span class="hljs-string">"\""</span> + string.replace(escapable, <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">(a)</span> </span>{
<span class="hljs-keyword">var</span> c = meta[a];
<span class="hljs-keyword">return</span> <span class="hljs-keyword">typeof</span> c === <span class="hljs-string">"string"</span> ? c
: <span class="hljs-string">"\\u"</span> + (<span class="hljs-string">"0000"</span> + a.charCodeAt(<span class="hljs-number">0</span>).toString(<span class="hljs-number">16</span>)).slice(-<span class="hljs-number">4</span>);
}) + <span class="hljs-string">"\""</span> : <span class="hljs-string">"\""</span> + string + <span class="hljs-string">"\""</span>;
}
<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">str</span><span class="hljs-params">(key, holder)</span> </span>{</pre></div></div>
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<p>Produce a string from holder[key].</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">var</span> i, <span class="hljs-comment">// The loop counter.</span>
k, <span class="hljs-comment">// The member key.</span>
v, <span class="hljs-comment">// The member value.</span>
length,
mind = gap,
partial,
value = holder[key];</pre></div></div>
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<p>If the value has a tojson method, call it to obtain a replacement value.</p>
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<span class="hljs-keyword">if</span> (value && <span class="hljs-keyword">typeof</span> value === <span class="hljs-string">"object"</span> &&
<span class="hljs-keyword">typeof</span> value.tojson === <span class="hljs-string">"function"</span>) {
value = value.tojson(key);
}</pre></div></div>
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<p>If we were called with a replacer function, then call the replacer to
obtain a replacement value.</p>
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<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> rep === <span class="hljs-string">"function"</span>) {
value = rep.call(holder, key, value);
}</pre></div></div>
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<p>What happens next depends on the value”s type.</p>
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<span class="hljs-keyword">switch</span> (<span class="hljs-keyword">typeof</span> value) {
<span class="hljs-keyword">case</span> <span class="hljs-string">"string"</span>:
<span class="hljs-keyword">return</span> quote(value);
<span class="hljs-keyword">case</span> <span class="hljs-string">"number"</span>:</pre></div></div>
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<p>json numbers must be finite. Encode non-finite numbers as null.</p>
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<span class="hljs-keyword">return</span> <span class="hljs-built_in">isFinite</span>(value) ? <span class="hljs-built_in">String</span>(value) : <span class="hljs-string">"null"</span>;
<span class="hljs-keyword">case</span> <span class="hljs-string">"boolean"</span>:
<span class="hljs-keyword">case</span> <span class="hljs-string">"null"</span>:</pre></div></div>
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<p>If the value is a boolean or null, convert it to a string. Note:
typeof null does not produce “null”. The case is included here in
the remote chance that this gets fixed someday.</p>
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<span class="hljs-keyword">return</span> <span class="hljs-built_in">String</span>(value);</pre></div></div>
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<p>If the type is “object”, we might be dealing with an object or an array or
null.</p>
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<span class="hljs-keyword">case</span> <span class="hljs-string">"object"</span>:</pre></div></div>
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<p>Due to a specification blunder in ECMAScript, typeof null is “object”,
so watch out for that case.</p>
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<span class="hljs-keyword">if</span> (!value) {
<span class="hljs-keyword">return</span> <span class="hljs-string">"null"</span>;
}</pre></div></div>
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<p>Make an array to hold the partial results of stringifying this object value.</p>
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gap += indent;
partial = [];</pre></div></div>
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<p>Is the value an array?</p>
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<span class="hljs-keyword">if</span> (<span class="hljs-built_in">Object</span>.prototype.toString.apply(value) === <span class="hljs-string">"[object Array]"</span>) {</pre></div></div>
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<p>The value is an array. Stringify every element. Use null as a placeholder
for non-json values.</p>
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<div class="content"><div class='highlight'><pre>
length = value.length;
<span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>; i < length; i += <span class="hljs-number">1</span>) {
partial[i] = str(i, value) || <span class="hljs-string">"null"</span>;
}</pre></div></div>
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<p>Join all of the elements together, separated with commas, and wrap them in
brackets.</p>
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v = partial.length === <span class="hljs-number">0</span> ? <span class="hljs-string">"[]"</span>
: gap ? <span class="hljs-string">"[\n"</span> + gap + partial.join(<span class="hljs-string">",\n"</span> + gap) + <span class="hljs-string">"\n"</span> + mind + <span class="hljs-string">"]"</span>
: <span class="hljs-string">"["</span> + partial.join(<span class="hljs-string">","</span>) + <span class="hljs-string">"]"</span>;
gap = mind;
<span class="hljs-keyword">return</span> v;
}</pre></div></div>
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<p>If the replacer is an array, use it to select the members to be stringified.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">if</span> (rep && <span class="hljs-keyword">typeof</span> rep === <span class="hljs-string">"object"</span>) {
length = rep.length;
<span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>; i < length; i += <span class="hljs-number">1</span>) {
<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> rep[i] === <span class="hljs-string">"string"</span>) {
k = rep[i];
v = str(k, value);
<span class="hljs-keyword">if</span> (v) {
partial.push(quote(k) + (gap ? <span class="hljs-string">": "</span> : <span class="hljs-string">":"</span>) + v);
}
}
}
} <span class="hljs-keyword">else</span> {</pre></div></div>
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<p>Otherwise, iterate through all of the keys in the object.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">for</span> (k <span class="hljs-keyword">in</span> value) {
<span class="hljs-keyword">if</span> (<span class="hljs-built_in">Object</span>.prototype.hasOwnProperty.call(value, k)) {
v = str(k, value);
<span class="hljs-keyword">if</span> (v) {
partial.push(quote(k) + (gap ? <span class="hljs-string">": "</span> : <span class="hljs-string">":"</span>) + v);
}
}
}
}</pre></div></div>
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<p>Join all of the member texts together, separated with commas,
and wrap them in braces.</p>
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<div class="content"><div class='highlight'><pre>
v = partial.length === <span class="hljs-number">0</span> ? <span class="hljs-string">"{}"</span>
: gap ? <span class="hljs-string">"{\n"</span> + gap + partial.join(<span class="hljs-string">",\n"</span> + gap) + <span class="hljs-string">"\n"</span> + mind + <span class="hljs-string">"}"</span>
: <span class="hljs-string">"{"</span> + partial.join(<span class="hljs-string">","</span>) + <span class="hljs-string">"}"</span>;
gap = mind;
<span class="hljs-keyword">return</span> v;
}
}</pre></div></div>
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<p>If the json object does not yet have a stringify method, give it one.</p>
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<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> json.stringify !== <span class="hljs-string">"function"</span>) {
json.stringify = <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">(value, replacer, space)</span> </span>{</pre></div></div>
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<p>The stringify method takes a value and an optional replacer, and an optional
space parameter, and returns a json text. The replacer can be a function
that can replace values, or an array of strings that will select the keys.
A default replacer method can be provided. Use of the space parameter can
produce text that is more easily readable.</p>
</div>
<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">var</span> i;
gap = <span class="hljs-string">""</span>;
indent = <span class="hljs-string">""</span>;</pre></div></div>
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<p>If the space parameter is a number, make an indent string containing that
many spaces.</p>
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<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> space === <span class="hljs-string">"number"</span>) {
<span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>; i < space; i += <span class="hljs-number">1</span>) {
indent += <span class="hljs-string">" "</span>;
}</pre></div></div>
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<p>If the space parameter is a string, it will be used as the indent string.</p>
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<div class="content"><div class='highlight'><pre>
} <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> space === <span class="hljs-string">"string"</span>) {
indent = space;
}</pre></div></div>
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<p>If there is a replacer, it must be a function or an array.
Otherwise, throw an error.</p>
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<div class="content"><div class='highlight'><pre>
rep = replacer;
<span class="hljs-keyword">if</span> (replacer && <span class="hljs-keyword">typeof</span> replacer !== <span class="hljs-string">"function"</span> &&
(<span class="hljs-keyword">typeof</span> replacer !== <span class="hljs-string">"object"</span> ||
<span class="hljs-keyword">typeof</span> replacer.length !== <span class="hljs-string">"number"</span>)) {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">Error</span>(<span class="hljs-string">"json.stringify"</span>);
}</pre></div></div>
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<p>Make a fake root object containing our value under the key of “”.
Return the result of stringifying the value.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">return</span> str(<span class="hljs-string">""</span>, {<span class="hljs-string">""</span>: value});
};
}</pre></div></div>
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<p>If the json object does not yet have a parse method, give it one.</p>
</div>
<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> json.parse !== <span class="hljs-string">"function"</span>) {
json.parse = <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">(text, reviver)</span> </span>{</pre></div></div>
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<p>The parse method takes a text and an optional reviver function, and returns
a JavaScript value if the text is a valid json text.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">var</span> j;
<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">walk</span><span class="hljs-params">(holder, key)</span> </span>{</pre></div></div>
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<p>The walk method is used to recursively walk the resulting structure so
that modifications can be made.</p>
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<div class="content"><div class='highlight'><pre>
<span class="hljs-keyword">var</span> k, v, value = holder[key];
<span class="hljs-keyword">if</span> (value && <span class="hljs-keyword">typeof</span> value === <span class="hljs-string">"object"</span>) {
<span class="hljs-keyword">for</span> (k <span class="hljs-keyword">in</span> value) {
<span class="hljs-keyword">if</span> (<span class="hljs-built_in">Object</span>.prototype.hasOwnProperty.call(value, k)) {
v = walk(value, k);
<span class="hljs-keyword">if</span> (v !== <span class="hljs-literal">undefined</span>) {
value[k] = v;
} <span class="hljs-keyword">else</span> {
<span class="hljs-keyword">delete</span> value[k];
}
}
}
}
<span class="hljs-keyword">return</span> reviver.call(holder, key, value);
}</pre></div></div>
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<p>Parsing happens in four stages. In the first stage, we replace certain
Unicode characters with escape sequences. JavaScript handles many characters
incorrectly, either silently deleting them, or treating them as line endings.</p>
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text = <span class="hljs-built_in">String</span>(text);
cx.lastIndex = <span class="hljs-number">0</span>;
<span class="hljs-keyword">if</span> (cx.test(text)) {
text = text.replace(cx, <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">(a)</span> </span>{
<span class="hljs-keyword">return</span> <span class="hljs-string">"\\u"</span> +
(<span class="hljs-string">"0000"</span> + a.charCodeAt(<span class="hljs-number">0</span>).toString(<span class="hljs-number">16</span>)).slice(-<span class="hljs-number">4</span>);
});
}</pre></div></div>
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<p>In the second stage, we run the text against regular expressions that look
for non-json patterns. We are especially concerned with “()” and “new”
because they can cause invocation, and “=” because it can cause mutation.
But just to be safe, we want to reject all unexpected forms.</p>
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<p>We split the second stage into 4 regexp operations in order to work around
crippling inefficiencies in IE’s and Safari’s regexp engines. First we
replace the json backslash pairs with “@” (a non-json character). Second, we
replace all simple value tokens with “]” characters. Third, we delete all
open brackets that follow a colon or comma or that begin the text. Finally,
we look to see that the remaining characters are only whitespace or “]” or
“,” or “:” or “{“ or “}”. If that is so, then the text is safe for eval.</p>
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<span class="hljs-keyword">if</span> (<span class="hljs-regexp">/^[\],:{}\s]*$/</span>
.test(text.replace(<span class="hljs-regexp">/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g</span>, <span class="hljs-string">"@"</span>)
.replace(<span class="hljs-regexp">/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g</span>, <span class="hljs-string">"]"</span>)
.replace(<span class="hljs-regexp">/(?:^|:|,)(?:\s*\[)+/g</span>, <span class="hljs-string">""</span>))) {</pre></div></div>
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<p>In the third stage we use the eval function to compile the text into a
JavaScript structure. The “{“ operator is subject to a syntactic ambiguity
in JavaScript: it can begin a block or an object literal. We wrap the text
in parens to eliminate the ambiguity.</p>
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j = <span class="hljs-built_in">eval</span>(<span class="hljs-string">"("</span> + text + <span class="hljs-string">")"</span>);</pre></div></div>
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<p>In the optional fourth stage, we recursively walk the new structure, passing
each name/value pair to a reviver function for possible transformation.</p>
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<span class="hljs-keyword">return</span> <span class="hljs-keyword">typeof</span> reviver === <span class="hljs-string">"function"</span> ? walk({<span class="hljs-string">""</span>: j}, <span class="hljs-string">""</span>) : j;
}</pre></div></div>
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<p>If the text is not json parseable, then a SyntaxError is thrown.</p>
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<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">SyntaxError</span>(<span class="hljs-string">"json.parse"</span>);
};
}
}());</pre></div></div>
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