noParameterAssign
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Diagnostic Category: lint/style/noParameterAssign
Since: v1.0.0
Sources:
- Same as:
no-param-reassign
Disallow reassigning function parameters.
Assignment to a function parameters can be misleading and confusing,
as modifying parameters will also mutate the arguments object.
It is often unintended and indicative of a programmer error.
In contrast to the ESLint rule, this rule cannot be configured to report assignments to a property of a parameter.
Examples
Section titled ExamplesInvalid
Section titled Invalidfunction f(param) { param = 13;}code-block.js:2:5 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Reassigning a function parameter is confusing.
1 │ function f(param) {
> 2 │ param = 13;
│ ^^^^^
3 │ }
4 │
ℹ The parameter is declared here:
> 1 │ function f(param) {
│ ^^^^^
2 │ param = 13;
3 │ }
ℹ Use a local variable instead.
function f(param) { param++;}code-block.js:2:5 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Reassigning a function parameter is confusing.
1 │ function f(param) {
> 2 │ param++;
│ ^^^^^
3 │ }
4 │
ℹ The parameter is declared here:
> 1 │ function f(param) {
│ ^^^^^
2 │ param++;
3 │ }
ℹ Use a local variable instead.
function f(param) { for (param of arr) {}}code-block.js:2:10 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Reassigning a function parameter is confusing.
1 │ function f(param) {
> 2 │ for (param of arr) {}
│ ^^^^^
3 │ }
4 │
ℹ The parameter is declared here:
> 1 │ function f(param) {
│ ^^^^^
2 │ for (param of arr) {}
3 │ }
ℹ Use a local variable instead.
class C { constructor(readonly prop: number) { prop++ }}code-block.ts:3:9 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
✖ Reassigning a function parameter is confusing.
1 │ class C {
2 │ constructor(readonly prop: number) {
> 3 │ prop++
│ ^^^^
4 │ }
5 │ }
ℹ The parameter is declared here:
1 │ class C {
> 2 │ constructor(readonly prop: number) {
│ ^^^^^^^^^^^^
3 │ prop++
4 │ }
ℹ Use a local variable instead.
Valid
Section titled Validfunction f(param) { let local = param;}