is javascript case sensitive with code examples

JavaScript is a programming language that powers many websites and web applications. Syntax and coding standards are significant in programming languages; every programming language operates with its rules and guidelines. One critical aspect that developers need to comprehend about JavaScript is its case sensitivity. In this article, we would discuss the concept of the case sensitivity of JavaScript, what it entails, its importance, and code examples.

Case Sensitivity in JavaScript

Case sensitivity is the attribute of a programming language whereby the language recognizes the difference between uppercase and lowercase letters. If a programming language supports case sensitivity, any uppercase and corresponding lowercase letters of an identifier would have different meanings in the code.

In other words, if a JavaScript program uses lowercase letters for an identifier in one instance and switches to uppercase in another instance, the interpreter would not identify them as the same thing and could cause syntax errors. Therefore, it is essential to ensure consistency in the use of uppercase and lowercase letters when writing JavaScript code.

For instance, consider the following code example:

var dish = "Pizza";
var Dish = "Cake";

Here, two identifiers dish and Dish are being declared. The dish identifier is being assigned the value of "Pizza," and the latter is assigned the value "Cake." The use of upper and lower case letters could seem interchangeable, but in reality, JavaScript treats them as separate entities. Hence, developers have to be careful in their declarations and generally adhere to standard coding conventions.

Importance of Case Sensitivity in JavaScript

The case sensitivity of JavaScript is crucial in ensuring that programming code is written to high standards. It also ensures that the code performs according to its intended purpose. Programming languages that are not case sensitive would accept code in any format, and this could lead to the developer's production of erroneous code.

JavaScript's case sensitivity feature ensures that identifiers with the same spelling but different capitalization are not treated as the same thing. This enables developers to create programs with more concise and accurate code.

For instance, consider this piece of code:

var apple = "apple";
Var Apple = "Apple";

In the code example above, the use of different cases gives the identifiers a different meaning. In this case, the first identifier "apple" is assigned the value "apple," while the second identifier, "Apple," is assigned the value "Apple." If a developer tries to use the identifier "apple" where "Apple" is required, the program would fail as "apple" and "Apple" are not the same in the code.

Code Examples

Below are simple code examples that show the case sensitivity of JavaScript in action.

Example 1:
var exampleVar = "Sample text";
VAR ExampleVar = "Different sample text";
console.log(exampleVar); //Outputs "Sample text"
console.log(ExampleVar); //Outputs "Different sample text"

In the example above, two specific variables are declared with different casing in their respective names. The first variable name uses camel-case, while the second variable name uses the upper-case format for the first letter of each word. The console output shows that both variables point to different data due to their casing.

Example 2:
var example = "Example text";
console.log(EXAMPLE); //Outputs an error

In the example above, an error occurs when referring to the variable with a different casing than the one used in the declaration. The console output shows that JavaScript recognizes the difference in syntax and the mismatch and issues an appropriate error message.


JavaScript is a case-sensitive programming language, and developers must adhere to standard coding conventions to avoid errors. The language considers variables with different cases as separate entities, and thus developers must use them carefully. Generally, it's essential to stay consistent with the casing used throughout the code to make it easier to read and avoid breaking the syntax rules.

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Popular questions

Certainly! Here are 5 questions regarding whether JavaScript is case sensitive, along with their respective answers:

Q1. What is case sensitivity in JavaScript?
A1. Case sensitivity is the property of recognizing the difference between uppercase and lowercase letters in JavaScript. Identifiers with the same spelling but different capitalization are treated as different entities in the code.

Q2. What happens if we mix uppercase and lowercase letters in a JavaScript identifier?
A2. If JavaScript code uses uppercase and lowercase letters interchangeably in an identifier, it could cause syntax errors because JavaScript cannot distinguish between the identifiers with different capitalization.

Q3. Why is it important to be consistent in using uppercase and lowercase letters in coding JavaScript?
A3. It is important to be consistent with the use of uppercase and lowercase letters when coding in JavaScript because JavaScript is case sensitive. Identifiers with similar spellings but varying capitalization are treated as unique entities, which can cause unexpected errors in the code.

Q4. Can we use the same identifier with different capitalization in different parts of the code in JavaScript?
A4. Yes, we can, but it is not recommended. The use of the same identifier with different capitalization in different parts of the code can confuse the interpreter and lead to syntax errors.

Q5. What happens if we try to call a variable in JavaScript with a different case than its original declaration?
A5. If we try to call a variable in JavaScript with a different case than its declaration, we will receive an error message. JavaScript considers the variables with different cases as separate entities, and any mismatching in spelling will result in an error.



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