Require Consistent This (consistent-this)

It is often necessary to capture the current execution context in order to make it available subsequently. A prominent example of this are jQuery callbacks:

var self = this;
jQuery('li').click(function (event) {
    // here, "this" is the HTMLElement where the click event occurred

There are many commonly used aliases for this such as self, that or me. It is desirable to ensure that whichever alias the team agrees upon is used consistently throughout the application.

Rule Details

This rule designates a variable as the chosen alias for “this”. It then enforces two things:

Assuming that alias is self, the following patterns are considered warnings:

var self = 42;

var that = this;

self = 42;

that = this;

The following patterns are considered okay and do not cause warnings:

var self = this;

var that = 42;

var that;

self = this; = this;

A declaration of an alias does not need to assign this in the declaration, but it must perform an appropriate assignment in the same scope as the declaration. The following patterns are also considered okay:

var self;
self = this;

var foo, self;
foo = 42;
self = this;

But the following pattern is considered a warning:

var self;
function f() {
    self = this;


This rule is disabled by default. You can configure the designated this variable:

"consistent-this": [0, "self"]

When Not To Use It

If you need to capture nested context, consistent-this is going to be problematic. Code of that nature is usually difficult to read and maintain and you should consider refactoring it.


This rule was introduced in ESLint 0.0.9.