Disallow new For Side Effects (no-new)

The goal of using new with a constructor is typically to create an object of a particular type and store that object in a variable, such as:

var person = new Person();

It's less common to use new and not store the result, such as:

new Person();

In this case, the created object is thrown away because its reference isn't stored anywhere, and in many cases, this means that the constructor should be replaced with a function that doesn't require new to be used.

Rule Details

This rule is aimed at maintaining consistency and convention by disallowing constructor calls using the new keyword that do not assign the resulting object to a variable.

Examples of incorrect code for this rule:

/*eslint no-new: "error"*/
 
new Thing();

Examples of correct code for this rule:

/*eslint no-new: "error"*/
 
var thing = new Thing();
 
Thing();

Source: http://eslint.org/docs/rules/

Disallow Use of Alert (no-alert)

JavaScript's alert, confirm, and prompt functions are widely considered to be obtrusive as UI elements and should be replaced by a more appropriate custom UI implementation. Furthermore, alert is often used while debugging code, which should be removed before deployment to production.

alert("here!");

Rule Details

This rule is aimed at catching debugging code that should be removed and popup UI elements that should be replaced with less obtrusive, custom UIs. As such, it will warn when it encounters alert, prompt, and confirm function calls which are not shadowed.

Examples of incorrect code for this rule:

/*eslint no-alert: "error"*/
 
alert("here!");
 
confirm("Are you sure?");
 
prompt("What's your name?", "John Doe");

Examples of correct code for this rule:

/*eslint no-alert: "error"*/
 
customAlert("Something happened!");
 
customConfirm("Are you sure?");
 
customPrompt("Who are you?");
 
function foo() {
    var alert = myCustomLib.customAlert;
    alert();
}

Related Rules

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