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.
This rule is aimed at enforcing a consistent way to check whether a string starts or ends with a specific string.
Examples of incorrect code for this rule:
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);
Examples of correct code for this rule:
foo.startsWith('bar'); foo.endsWith('bar');
There are no options.
{ "@typescript-eslint/prefer-string-starts-ends-with": "error" }
If you don't mind that style, you can turn this rule off safely.