mirror of
https://git.proxmox.com/git/pve-eslint
synced 2025-10-05 05:20:49 +00:00
eb39fafa4f
includes a (minimal) working wrapper Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
93 lines
2.3 KiB
Markdown
93 lines
2.3 KiB
Markdown
# disallow ternary operators when simpler alternatives exist (no-unneeded-ternary)
|
|
|
|
It's a common mistake in JavaScript to use a conditional expression to select between two Boolean values instead of using ! to convert the test to a Boolean.
|
|
Here are some examples:
|
|
|
|
```js
|
|
// Bad
|
|
var isYes = answer === 1 ? true : false;
|
|
|
|
// Good
|
|
var isYes = answer === 1;
|
|
|
|
|
|
// Bad
|
|
var isNo = answer === 1 ? false : true;
|
|
|
|
// Good
|
|
var isNo = answer !== 1;
|
|
```
|
|
|
|
Another common mistake is using a single variable as both the conditional test and the consequent. In such cases, the logical `OR` can be used to provide the same functionality.
|
|
Here is an example:
|
|
|
|
```js
|
|
// Bad
|
|
foo(bar ? bar : 1);
|
|
|
|
// Good
|
|
foo(bar || 1);
|
|
```
|
|
|
|
## Rule Details
|
|
|
|
This rule disallow ternary operators when simpler alternatives exist.
|
|
|
|
Examples of **incorrect** code for this rule:
|
|
|
|
```js
|
|
/*eslint no-unneeded-ternary: "error"*/
|
|
|
|
var a = x === 2 ? true : false;
|
|
|
|
var a = x ? true : false;
|
|
```
|
|
|
|
Examples of **correct** code for this rule:
|
|
|
|
```js
|
|
/*eslint no-unneeded-ternary: "error"*/
|
|
|
|
var a = x === 2 ? "Yes" : "No";
|
|
|
|
var a = x !== false;
|
|
|
|
var a = x ? "Yes" : "No";
|
|
|
|
var a = x ? y : x;
|
|
|
|
f(x ? x : 1); // default assignment - would be disallowed if defaultAssignment option set to false. See option details below.
|
|
```
|
|
|
|
## Options
|
|
|
|
This rule has an object option:
|
|
|
|
* `"defaultAssignment": true` (default) allows the conditional expression as a default assignment pattern
|
|
* `"defaultAssignment": false` disallows the conditional expression as a default assignment pattern
|
|
|
|
### defaultAssignment
|
|
|
|
When set to `true`, which it is by default, The defaultAssignment option allows expressions of the form `x ? x : expr` (where `x` is any identifier and `expr` is any expression).
|
|
|
|
Examples of additional **incorrect** code for this rule with the `{ "defaultAssignment": false }` option:
|
|
|
|
```js
|
|
/*eslint no-unneeded-ternary: ["error", { "defaultAssignment": false }]*/
|
|
|
|
var a = x ? x : 1;
|
|
|
|
f(x ? x : 1);
|
|
```
|
|
|
|
Note that `defaultAssignment: false` still allows expressions of the form `x ? expr : x` (where the identifier is on the right hand side of the ternary).
|
|
|
|
## When Not To Use It
|
|
|
|
You can turn this rule off if you are not concerned with unnecessary complexity in conditional expressions.
|
|
|
|
## Related Rules
|
|
|
|
* [no-ternary](no-ternary.md)
|
|
* [no-nested-ternary](no-nested-ternary.md)
|