Disallow Self Assignment (no-self-assign)

Self assignments have no effect, so probably those are an error due to incomplete refactoring. Those indicate that what you should do is still remaining.

foo = foo;
[bar, baz] = [bar, qiz];

Rule Details

This rule is aimed at eliminating self assignments.

Examples of incorrect code for this rule:

/*eslint no-self-assign: "error"*/

foo = foo;

[a, b] = [a, b];

[a, ...b] = [x, ...b];

({a, b} = {a, x});

Examples of correct code for this rule:

/*eslint no-self-assign: "error"*/

foo = bar;
[a, b] = [b, a];

// This pattern is warned by the `no-use-before-define` rule.
let foo = foo;

// The default values have an effect.
[foo = 1] = [foo];

Options

This rule has the option to check properties as well.

{
    "no-self-assign": ["error", {"props": false}]
}

props

Examples of incorrect code for the { "props": true } option:

/*eslint no-self-assign: ["error", {"props": true}]*/

// self-assignments with properties.
obj.a = obj.a;
obj.a.b = obj.a.b;
obj["a"] = obj["a"];
obj[a] = obj[a];

Examples of correct code for the { "props": true } option:

/*eslint no-self-assign: ["error", {"props": true}]*/

// non-self-assignments with properties.
obj.a = obj.b;
obj.a.b = obj.c.b;
obj.a.b = obj.a.c;
obj[a] = obj["a"]

// This ignores if there is a function call.
obj.a().b = obj.a().b
a().b = a().b

// Known limitation: this does not support computed properties except single literal or single identifier.
obj[a + b] = obj[a + b];
obj["a" + "b"] = obj["a" + "b"];

When Not To Use It

If you don’t want to notify about self assignments, then it’s safe to disable this rule.

Version

This rule was introduced in ESLint 2.0.0-rc.0.

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