Is JavaScript Case Sensitive?

Is JavaScript Case Sensitive?
Written by Sagar RabidasMarch 1, 2022
10 min read
Sagar Rabidas

Software Developer

in this blog, we will discuss Is JavaScript Case Sensitive or not.

Introduction of JavaScript:-

Javascript is a dynamic web scripting language. It’s maximum normally used as a language of internet content material, whose implementations permit the consumer-side script to behave with the person and construct dynamic pages. It’s an interpreted synthetic language with item-orientated abilities.

Javascript become 1st known as LiveScript, but, the browser changed its call to javascript, presumably due to the joy being generated by using java. Javascript created its creation with the call LiveScript. The general middle of the language has been embedded inside the browser.

JavaScript Features:-

  • JavaScript is a lightweight, artificial, an interpreted language.
  • Used for making network-centric applications.
  • Integrated with Java.
  • Integrated with a hypertext markup language.
  • Open and cross-platform


Textual content that’s sensitive to the capitalization of letters. For example, “Laptop” and “Computer” are 2 one-of-a-kind phrases as a result of the “C” being uppercase within the 1st instance and lowercase in the second instance. On modern structures, passwords are case-touchy, and usernames are every so often case-touchy furthermore.

Whatever that’s a no longer case-touchy method any uppercase or little person is often entered. As an instance, the windows software line or MS-DOS isn’t case-sensitive, but, the Linux program line is case sensitive.

Why is case sensitivity so much more important in JavaScript:-

It’s the character of the beast. A script is written in undeniable textual content, for starters, however, it’s no longer truly markup like hypertext markup language (that is case-insensitive) its code, and challenge to as a substitute more scrutiny through the browser’s inner workings (DOM APIs).

var names, Names;

The 2 variables look-alike, nearly, however, to javascript their worlds aside. What’s critical is that we tend to acknowledge it, now not by using its significance, but by using its terrible nature. It’s what it’s.

function Person(name, age)
var person = new Person("Zach", 29);

We can ignore the make-up of this code considering that gadgets might not be lined, but. The cause right here is to factor out that individual and individual are 2 utterly one-of-a-kind objects. The character is an object builder function, and someone is an instance of that builder class.


Because it stands, we generally tend to all ought to check our capitalization or meet with workable bad effects like syntax mistakes, reference mistakes, and distinct exceptions. Make a keen eye, and keep a reminder that javascript is case touchy.

Why is JavaScript Case Sensitive but HTML isn’t:-

A script is in undeniable textual content and no longer honestly markup like hypertext markup language, which is case insensitive. In javascript, the while keyword has to be “even as”, now not “while” or “at the same time as”. Case sensitivity may be very essential because it’s closely associated with a hypertext markup language, however, a few ways and events are referred to in any other case. Javascript functions a strict syntax to a method the customer-side-scripts written in javascript. A few tags and attributes in hypertext markup language have an equal call as javascript items and properties. In HTML, the characteristics and tag names are case-insensitive. The shut affiliation of hypertext markup language and javascript will confuse, therefore case sensitivity is moreover important in javascript.

The following two words in JavaScript are completely different:

var demo;
var DEMO;

The following are different objects due to the Javascript case-sensitive features:

function Employee(id, name, subject){ = id; = name;
var employee = new Employee("ee1", “John”,”30”);

While operating with JavaScript, do check for capitalization of a variable, operate and object name. This can stop syntax and different errors.

Is Javascript Case Sensitive:-

Javascript is a case-sensitive language. This implies that the language key phrases, variables, function names, and the alternative identifiers must be typewritten with an equal capitalization of letters.

So the identifiers Time and TIME can convey different meanings in JavaScript.

The following example shows JavaScript is a case-sensitive language:

<!DOCTYPE html>
<h3>My favorite subject</h3>
<p id="demo"></p>
var subject, Subject;
subject = "Java";
Subject = "Maths";
document.getElementById("demo").innerHTML = subject;

Suppose we want to find the string variable needle in the string variable haystack. There are three gotchas:

  1. Internationalized programs have to avoid string.toUppercase and string.toLowercase. Use a daily expression that ignores the case alternatively.For instance, volt-ampere needleRegExp = new RegExp(needle, “i”); followed by needleRegExp.test(haystack).
  2. In standard, you'll likely no longer recognize the worth of the needle. Take care that the needle doesn’t incorporate any normal expression special characters. Escape this exploitation needle.Replace(/[-[\]()*+?.,\\^$|#\s]/g, “\\$&”);.
  3. In different cases, if you wish to exactly match needle and hayrick, simply ignoring the case, ensure to feature “^” at the beginning and “$” at the tip of your regular expression builder.

Taking points (1) and (2) into thought, an example would be:

var haystack = "A. BAIL. Of. Hay.";
var needle = "bail.";
var needleRegExp = new RegExp(needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"), "i");
var result = needleRegExp.test(haystack);
if (result) {
// Your code here


So thinking about the above points we can say that javascript is a case-touchy scripting language. This means is that the language considers capital letters as completely special from their little opposite numbers. As an instance, in case you declare a variable referred to as general value in javascript, you have got to apply the general fee to see that variable, not the total cost, general cost, or every other mixture.

In javascript, the case sensitivity doesn’t virtually practice to variable names but moreover to javascript keywords, occasion handlers, and item houses or ways. Key phrases in javascript are all little, for example, whilst, for, if, else, and so on. On the opposite hand, ways (homes) use “camel-again” naming conference (the primary phrase is in little and each ordered 1st letter of each phrase is capitalized), as an example, array(), last-modified(), and so on.

Case Sensitive
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