We cannot modify variables that are declared using const keyword. It will raise a runtime error.
Under non ES2015 environment, it might be ignored merely.
Rule Details ​
This rule is aimed to flag modifying variables that are declared using const keyword.
Examples of incorrect code for this rule:
::: incorrect
js
/*eslint no-const-assign: "error"*/
const a = 0;
a = 1;:::
::: incorrect
js
/*eslint no-const-assign: "error"*/
const a = 0;
a += 1;:::
::: incorrect
js
/*eslint no-const-assign: "error"*/
const a = 0;
++a;:::
Examples of correct code for this rule:
::: correct
js
/*eslint no-const-assign: "error"*/
const a = 0;
console.log(a);:::
::: correct
js
/*eslint no-const-assign: "error"*/
for (const a in [1, 2, 3]) { // `a` is re-defined (not modified) on each loop step.
console.log(a);
}:::
::: correct
js
/*eslint no-const-assign: "error"*/
for (const a of [1, 2, 3]) { // `a` is re-defined (not modified) on each loop step.
console.log(a);
}:::
When Not To Use It ​
If you don't want to be notified about modifying variables that are declared using const keyword, you can safely disable this rule.