return co(function* connect() {

Close

Disallow generator functions that do not have yield (require-yield)

Rule Details

This rule generates warnings for generator functions that do not have the yield keyword.

Examples

Examples of incorrect code for this rule:

/*eslint require-yield: "error"*/
/*eslint-env es6*/

function* foo() {
  return 10;
}

Examples of correct code for this rule:

/*eslint require-yield: "error"*/
/*eslint-env es6*/

function* foo() {
  yield 5;
  return 10;
}

function foo() {
  return 10;
}

// This rule does not warn on empty generator functions.
function* foo() { }

When Not To Use It

If you don't want to notify generator functions that have no yield expression, then it's safe to disable this rule.

Related Rules

• [require-await](require-await.md) Source: http://eslint.org/docs/rules/

      func.apply(null, args);

Close

Suggest using the spread operator instead of .apply(). (prefer-spread)

Before ES2015, one must use Function.prototype.apply() to call variadic functions.

var args = [1, 2, 3, 4];
Math.max.apply(Math, args);

In ES2015, one can use the spread operator to call variadic functions.

/*eslint-env es6*/

var args = [1, 2, 3, 4];
Math.max(...args);

Rule Details

This rule is aimed to flag usage of Function.prototype.apply() in situations where the spread operator could be used instead.

Examples

Examples of incorrect code for this rule:

/*eslint prefer-spread: "error"*/

foo.apply(undefined, args);
foo.apply(null, args);
obj.foo.apply(obj, args);

Examples of correct code for this rule:

/*eslint prefer-spread: "error"*/

// Using the spread operator
foo(...args);
obj.foo(...args);

// The `this` binding is different.
foo.apply(obj, args);
obj.foo.apply(null, args);
obj.foo.apply(otherObj, args);

// The argument list is not variadic.
// Those are warned by the `no-useless-call` rule.
foo.apply(undefined, [1, 2, 3]);
foo.apply(null, [1, 2, 3]);
obj.foo.apply(obj, [1, 2, 3]);

Known limitations:

This rule analyzes code statically to check whether or not the this argument is changed. So, if the this argument is computed in a dynamic expression, this rule cannot detect a violation.

/*eslint prefer-spread: "error"*/

// This warns.
a[i++].foo.apply(a[i++], args);

// This does not warn.
a[++i].foo.apply(a[i], args);

When Not To Use It

This rule should not be used in ES3/5 environments.

In ES2015 (ES6) or later, if you don't want to be notified about Function.prototype.apply() callings, you can safely disable this rule.

Related Rules

• [no-useless-call](no-useless-call.md) Source: http://eslint.org/docs/rules/