ESLintconsistent-this
Enforces consistent naming when capturing the current execution context.
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 that = this;
jQuery('li').click(function (event) {
// here, "this" is the HTMLElement where the click event occurred
that.setFoo(42);
});
There are many commonly used aliases for this such as that, self or me. It is desirable to ensure that whichever alias the team agrees upon is used consistently throughout the application.
Rule Details
This rule enforces two things about variables with the designated alias names for this:
- If a variable with a designated name is declared, it must be either initialized (in the declaration) or assigned (in the same scope as the declaration) the value
this. - If a variable is initialized or assigned the value
this, the name of the variable must be a designated alias.
Options
This rule has one or more string options:
- designated alias names for
this(default"that")
Examples of incorrect code for this rule with the default "that" option:
/*eslint consistent-this: ["error", "that"]*/
var that = 42;
var self = this;
that = 42;
self = this;
Examples of correct code for this rule with the default "that" option:
/*eslint consistent-this: ["error", "that"]*/
var that = this;
var self = 42;
var self;
that = this;
foo.bar = this;
Examples of incorrect code for this rule with the default "that" option, if the variable is not initialized:
/*eslint consistent-this: ["error", "that"]*/
var that;
function f() {
that = this;
}
Examples of correct code for this rule with the default "that" option, if the variable is not initialized:
/*eslint consistent-this: ["error", "that"]*/
var that;
that = this;
var foo, that;
foo = 42;
that = this;
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.
Version
This rule was introduced in ESLint 0.0.9.