Enforce the use of String#startsWith
and String#endsWith
instead of other equivalent methods of checking substrings (prefer-string-starts-ends-with
)
There are multiple ways to verify if a string starts or ends with a specific string, such as foo.indexOf('bar') === 0
.
Since ES2015 has added String#startsWith
and String#endsWith
, this rule reports other ways to be consistent.
Rule Details
This rule is aimed at enforcing a consistent way to check whether a string starts or ends with a specific string.
Examples of code for this rule:
- โ Incorrect
- โ Correct
let foo: string;
// starts with
foo[0] === 'b';
foo.charAt(0) === 'b';
foo.indexOf('bar') === 0;
foo.slice(0, 3) === 'bar';
foo.substring(0, 3) === 'bar';
foo.match(/^bar/) != null;
/^bar/.test(foo);
// ends with
foo[foo.length - 1] === 'b';
foo.charAt(foo.length - 1) === 'b';
foo.lastIndexOf('bar') === foo.length - 3;
foo.slice(-3) === 'bar';
foo.substring(foo.length - 3) === 'bar';
foo.match(/bar$/) != null;
/bar$/.test(foo);
foo.startsWith('bar');
foo.endsWith('bar');
Options
There are no options.
{
"@typescript-eslint/prefer-string-starts-ends-with": "error"
}
When Not To Use It
If you don't mind that style, you can turn this rule off safely.
Attributes
- โ Recommended
- ๐ง Fixable
- ๐ญ Requires type information