How To Check If A Variable Is A String In JavaScript?

In this tutorial, we will see how to check if a variable is a string in javascript. typeof in js variable is a primitive value or an instance of a standard built-in ES (ECMAScript) object.

Sometimes the string that we get in a project, whether it is in a string or not, check if string javascript, we will see in this tutorial How to find string is string javascript.

We will learn 4 ways how to find out whether a string is there or not.

How To Check If A Variable Is A String In JavaScript? PhpCodingStuff

1. typeof operator

In this step, we will see the recommended solution is to use typeof operator to determine the type of the operand. See below:

const val = 'Hello World';
 
if (typeof val === 'string')
{
    console.log('Variable is a string');
}
else
{
    console.log('Variable is not a string');
}
 
/*
    Output: Variable is a string
*/

This time typeof operator will return an object for the string created with a new String(). string javascript can be handled using the instanceof the operator.

const val = new String('Hello World');
 
if (typeof val === 'string' || val instanceof String)
{
    console.log('Variable is a string');
}
else
{
    console.log('Variable is not a string');
}
 
/*
    Output: Variable is a string
*/

2. Object.prototype.toString.call()

Another example approach is to find the class of object using the toString method from Object.prototype. javascript test string this can be used as see below:

function isString(x) {
    return Object.prototype.toString.call(x) === '[object String]';
}
 
const val = 'Hello World';
 
if (isString(val))
{
    console.log('Variable is a string');
}
else
{
    console.log('Variable is not a string');
}
 
/*
    Output: Variable is a string
*/

3. Lodash/Underscore Library

check if string javascript if you're using the Underscore of Lodash library, consider using the _.isString a method which returns true for specified value javascript check if string is a string primitive or a String object.

const _ = require('lodash');        // or underscore
 
const val = new String('Hello World');
 
if (_.isString(val))
{
    console.log('Variable is a string');
}
else
{
    console.log('Variable is not a string');
}
 
/*
    Output: Variable is a string
*/

4. jQuery Library

In this step, we will learn how to check type of variable in javascript with jquery, $.type() a method that can be used to determine the type of object. java script check worked with both primitive string value and built-in String Object. See below:

const { JSDOM } = require("jsdom");
const { window } = new JSDOM();
const $ = require("jquery")(window);
 
const val = 'Hello World';
 
if ($.type(val) === 'string')
{
    console.log('Variable is a string');
}
else
{
    console.log('Variable is not a string');
}
 
/*
    Output: Variable is a string
*/

I hope it can help you...

JQuery Javascript

Robert look

Author, Web Developer (Front-end & Back-end)

My Name is Robert look from New york, America. I'm a Web Application Developer with 6 years of experience. Currently, I'm working on front-end & back-end web development using popular web technology Languages. That's why I love to share my coding knowledge in a smart way.