mirror of
https://git.proxmox.com/git/pve-eslint
synced 2025-10-05 07:04:54 +00:00
eb39fafa4f
includes a (minimal) working wrapper Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
125 lines
2.9 KiB
Markdown
125 lines
2.9 KiB
Markdown
# Disallow the type conversion with shorter notations. (no-implicit-coercion)
|
|
|
|
In JavaScript, there are a lot of different ways to convert value types.
|
|
Some of them might be hard to read and understand.
|
|
|
|
Such as:
|
|
|
|
```js
|
|
var b = !!foo;
|
|
var b = ~foo.indexOf(".");
|
|
var n = +foo;
|
|
var n = 1 * foo;
|
|
var s = "" + foo;
|
|
foo += ``;
|
|
```
|
|
|
|
Those can be replaced with the following code:
|
|
|
|
```js
|
|
var b = Boolean(foo);
|
|
var b = foo.indexOf(".") !== -1;
|
|
var n = Number(foo);
|
|
var n = Number(foo);
|
|
var s = String(foo);
|
|
foo = String(foo);
|
|
```
|
|
|
|
## Rule Details
|
|
|
|
This rule is aimed to flag shorter notations for the type conversion, then suggest a more self-explanatory notation.
|
|
|
|
## Options
|
|
|
|
This rule has three main options and one override option to allow some coercions as required.
|
|
|
|
* `"boolean"` (`true` by default) - When this is `true`, this rule warns shorter type conversions for `boolean` type.
|
|
* `"number"` (`true` by default) - When this is `true`, this rule warns shorter type conversions for `number` type.
|
|
* `"string"` (`true` by default) - When this is `true`, this rule warns shorter type conversions for `string` type.
|
|
* `"allow"` (`empty` by default) - Each entry in this array can be one of `~`, `!!`, `+` or `*` that are to be allowed.
|
|
|
|
Note that operator `+` in `allow` list would allow `+foo` (number coercion) as well as `"" + foo` (string coercion).
|
|
|
|
### boolean
|
|
|
|
Examples of **incorrect** code for the default `{ "boolean": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var b = !!foo;
|
|
var b = ~foo.indexOf(".");
|
|
// bitwise not is incorrect only with `indexOf`/`lastIndexOf` method calling.
|
|
```
|
|
|
|
Examples of **correct** code for the default `{ "boolean": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var b = Boolean(foo);
|
|
var b = foo.indexOf(".") !== -1;
|
|
|
|
var n = ~foo; // This is a just bitwise not.
|
|
```
|
|
|
|
### number
|
|
|
|
Examples of **incorrect** code for the default `{ "number": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var n = +foo;
|
|
var n = 1 * foo;
|
|
```
|
|
|
|
Examples of **correct** code for the default `{ "number": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var n = Number(foo);
|
|
var n = parseFloat(foo);
|
|
var n = parseInt(foo, 10);
|
|
```
|
|
|
|
### string
|
|
|
|
Examples of **incorrect** code for the default `{ "string": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var s = "" + foo;
|
|
var s = `` + foo;
|
|
foo += "";
|
|
foo += ``;
|
|
```
|
|
|
|
Examples of **correct** code for the default `{ "string": true }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: "error"*/
|
|
|
|
var s = String(foo);
|
|
foo = String(foo);
|
|
```
|
|
|
|
### allow
|
|
|
|
Using `allow` list, we can override and allow specific operators.
|
|
|
|
Examples of **correct** code for the sample `{ "allow": ["!!", "~"] }` option:
|
|
|
|
```js
|
|
/*eslint no-implicit-coercion: [2, { "allow": ["!!", "~"] } ]*/
|
|
|
|
var b = !!foo;
|
|
var b = ~foo.indexOf(".");
|
|
```
|
|
|
|
## When Not To Use It
|
|
|
|
If you don't want to be notified about shorter notations for the type conversion, you can safely disable this rule.
|