Disallow modifying variables that are declared using `const` (no-const-assign)

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.

The following patterns are considered warnings:

const a = 0;
a = 1;

const a = 0;
a += 1;

const a = 0;
++a;

The following patterns are not considered warnings:

const a = 0;
console.log(a);

for (const a in [1, 2, 3]) { // `a` is re-defined (not modified) on each loop step.
    console.log(a);
}

for (const a of [1, 2, 3]) { // `a` is re-defined (not modified) on each loop step.
    console.log(a);
}

If you don’t want to be notified about modifying variables that are declared using const keyword, you can safely disable this rule.

This rule was introduced in ESLint 1.0.0-rc-1.