Disallow assignments where both sides are exactly the same
The "extends": "eslint:recommended" property in a configuration file enables this rule
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];
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});
foo &&= foo;
foo ||= foo;
foo ??= foo;
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];
// 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;
// `&=` and `|=` have an effect on non-integers.
foo &= foo;
foo |= foo;
// 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"];
This rule has the option to check properties as well.
{
"no-self-assign": ["error", {"props": true}]
}
props - if this is true, no-self-assign rule warns self-assignments of properties. Default is true.Examples of correct code with the { "props": false } option:
/*eslint no-self-assign: ["error", {"props": false}]*/
// self-assignments with properties.
obj.a = obj.a;
obj.a.b = obj.a.b;
obj["a"] = obj["a"];
obj[a] = obj[a];
If you don’t want to notify about self assignments, then it’s safe to disable this rule.
This rule was introduced in ESLint v2.0.0-rc.0.
© OpenJS Foundation and other contributors
Licensed under the MIT License.
https://eslint.org/docs/latest/rules/no-self-assign