Enforce the use of === and !==

Documentos > Code Analysis > Static Analysis Rules > Enforce the use of === and !==

This page is not yet available in Spanish. We are working on its translation.
If you have any questions or feedback about our current translation project, feel free to reach out to us!

Metadata

ID: typescript-code-style/strict-equals

Language: TypeScript

Severity: Notice

Category: Best Practices

Description

In JavaScript, == and != comparisons do type coercion, which can be confusing and may introduce potential errors. Use the type-safe equality operators === and !== instead.

Non-Compliant Code Examples

a == b
a != b
typeof a == 'number'
typeof a == 'number'
'string' != typeof a
true == true
2 == 3
2 == 3
'hello' != 'world'
'hello' != 'world'
a == null
a == null
null != a
true == 1
0 != '1'
'wee' == /wee/
typeof a == 'number'
'string' != typeof a
'hello' != 'world'
2 == 3
true == true
true == null
true != null
null == null
null != null
a
==
b
(a) == b
(a) != b
a == (b)
a != (b)
(a) == (b)
(a == b) == (c)
(a != b) != (c)
a == b;
a!=b;
(a + b) == c;
(a + b)  !=  c;
((1) )  ==  (2);

Compliant Code Examples

a === b
a !== b
a === b
a !== null
a === null
a !== null
null === null
null !== null

// https://github.com/eslint/eslint/issues/8020
foo === /abc/u

// bigint
foo === 1n

foo != undefined