In JS null value means no value or absence of a value. Checking null in Javascript is easy, you can use the equality operator == or strict equality operator === (also called identity operator).
Examples of JavaScript checking null
Is the variable null? A code of Using equality operator to check null in JS.
if (a === null)Note:
- Abstract Equality Comparison (
==, also called “loose” equality) - Strict Equality Comparison (
===)
See the MDN article on Equality comparisons and sameness for more detail.
Complete Example
<!DOCTYPE html>
<html>
<body>
<script type="text/javascript">
var name_first= null;
if (name_first === null){
alert("name is null")
}
</script>
</body>
</html> Output:
Q: Is there a standard function to check for null, undefined, or blank variables in JavaScript?
Answer: You can just check if the variable has a truthy value or not.
if( value ) {
}will evaluate to true if value is not:
- null
- undefined
- NaN
- empty string (“”)
- 0
- false
Q: What is the Type of null in JavaScript?
Answer: null has the 0 type tag, which corresponds to an object. The value null represents the intentional absence of any object value
typeof null // "object"Do comment if you have any doubts and suggestions on this question.
Note: The All JS Examples codes are tested on the Safari browser (Version 12.0.2) and Chrome.
OS: macOS 10.14 Mojave
Code: HTML 5 Version