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noConstAssign

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Diagnostic Category: lint/correctness/noConstAssign

Since: v1.0.0

Sources:

Prevents from having const variables being re-assigned.

Trying to assign a value to a const will cause an TypeError when the code is executed.

const a = 1;
a = 4;
code-block.js:2:1 lint/correctness/noConstAssign  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Can’t assign a because it’s a constant

1 │ const a = 1;
> 2 │ a = 4;
^
3 │

This is where the variable is defined as constant

> 1 │ const a = 1;
^
2 │ a = 4;
3 │

Unsafe fix: Replace const with let if you assign it to a new value.

1 - const·a·=·1;
1+ let·a·=·1;
2 2 a = 4;
3 3

const a = 2;
a += 1;
code-block.js:2:1 lint/correctness/noConstAssign  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Can’t assign a because it’s a constant

1 │ const a = 2;
> 2 │ a += 1;
^
3 │

This is where the variable is defined as constant

> 1 │ const a = 2;
^
2 │ a += 1;
3 │

Unsafe fix: Replace const with let if you assign it to a new value.

1 - const·a·=·2;
1+ let·a·=·2;
2 2 a += 1;
3 3

const a = 1;
++a;
code-block.js:2:3 lint/correctness/noConstAssign  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Can’t assign a because it’s a constant

1 │ const a = 1;
> 2 │ ++a;
^
3 │

This is where the variable is defined as constant

> 1 │ const a = 1;
^
2 │ ++a;
3 │

Unsafe fix: Replace const with let if you assign it to a new value.

1 - const·a·=·1;
1+ let·a·=·1;
2 2 ++a;
3 3

const a = 1, b = 2;
a = 2;
code-block.js:3:1 lint/correctness/noConstAssign  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Can’t assign a because it’s a constant

1 │ const a = 1, b = 2;
2 │
> 3 │ a = 2;
^
4 │

This is where the variable is defined as constant

> 1 │ const a = 1, b = 2;
^
2 │
3 │ a = 2;

Unsafe fix: Replace const with let if you assign it to a new value.

1 - const·a·=·1,·b·=·2;
1+ let·a·=·1,·b·=·2;
2 2
3 3 a = 2;

const a = 10;
let b = 10;
b = 20;