Check if a variable is a string using JavaScript
Last Updated :
07 Dec, 2023
In this article, we will check if a variable is a string using JavaScript. We can check the variable by using many methods.
Below are the following methods through which we can check the type of variable is a string:
Approach 1: Using typeOf Operator
In this approach, we are using typeOf operator which tells us the type of the given value. we are getting the type of the value by the use of the typeOf operator and we are using if-else for returning our ans.
Example: This example shows the implementation of the above-explained approach.
Javascript
let boolValue = true ;
let numValue = 17;
let bool, num;
if ( typeof boolValue == "string" ) {
bool = "is a string" ;
} else {
bool = "is not a string" ;
}
if ( typeof numValue == "string" ) {
num = "is a string" ;
} else {
num = "is not a string" ;
}
console.log(bool);
console.log(num);
|
Output
is not a string
is not a string
Approach 2: Using Instanceof Operator
The instanceof operator in JavaScript is used to check the type of an object at run time.
Syntax:
let gfg = objectName instanceof objectType
Example: This example shows the implementation of above-explained appraoch.
Javascript
let variable = new String();
if (variable instanceof String) {
console.log( "variable is a string." );
} else {
console.log( "variable is not a string." );
}
|
Output
variable is a string.
The _.isString() function is used to check whether the given object element is string or not.
Syntax:
_.isString( object );
Example: This example shows the implementation of above-explained appraoch.
Javascript
let _ = required( "underscore" );
let info = {
Company: 'GeeksforGeeks' ,
Address: 'Noida' ,
Contact: '+91 9876543210'
};
console.log(_.isString(info));
let str = 'GeeksforGeeks' ;
console.log(_.isString(str));
|
Output:
false
true
In this approach, we are using the Lodah _.isString() method that returns boolean response for the given value.
Example: This example shows the implementation of above-explained appraoch.
Javascript
const _ = require( "lodash" );
console.log(_.isString( 'GeeksforGeeks' ));
console.log(_.isString( true ));
|
Output:
true
false
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