Is javascript script case sensitive?

JavaScript is a high-level programming language that is widely used in the development of web applications and mobile applications. When writing scripts in JavaScript, a common question is: Are JavaScript scripts case-sensitive? This article will give you a detailed introduction to whether JavaScript scripts are case-sensitive.

JavaScript is case-sensitive

The short answer is: Yes, JavaScript is case-sensitive. This means that in JavaScript, uppercase and lowercase letters are different characters.

For example, in JavaScript, the variable name "hello" and the variable name "Hello" are different variable names. This means that if you declare a variable named "hello" and then try to use a variable named "Hello" in your code, the system will treat it as an undefined variable, resulting in an error.

The same rules apply to identifiers such as names of variables, functions, and objects. JavaScript is case-sensitive, which is something you must pay attention to.

Sample code:

// 声明变量 myVar
var myVar = "hello";
var myvar = "world";

document.write(myVar); // 输出 "hello"
document.write(myvar); // 输出 "world"

In the above example, we declared two variables, one named "myVar" and the other named "myvar". We call document.write() to output two variables. Since JavaScript is case-sensitive, these two variables will output their respective initial values ​​separately.

Exact match or partial match?

In JavaScript, although it is not case sensitive, in some cases JavaScript will try to do a "partial match". For example, in HTML, we often use JavaScript to add event handlers to page elements. In this case, JavaScript attempts a "partial match" of the event handler's name.

Sample code:

<button onclick="myFunction()">点我</button>

<script>
function myFunction() {
  alert("Hello World!");
}
</script>

In the above example, we added an onclick event handler to a button element. In the name of the event handler, we used the lowercase letter "o" instead of the uppercase letter "O". Despite this, JavaScript is still able to correctly identify it and call the appropriate function when the button is clicked.

However, it is important to note that JavaScript does not attempt partial matching of function or variable names. If you try to use an undefined variable or function name in your code, JavaScript will throw an error.

Conclusion

To sum up, JavaScript scripts are case-sensitive. In JavaScript, uppercase and lowercase letters are different characters, so you must pay attention to uppercase and lowercase when defining variables, functions, or objects. At the same time, it's important to note that in some cases, JavaScript will attempt a "partial match" but still require an exact match when using variable or function names.

I hope this article can answer your doubts when using JavaScript, and also remind everyone to pay attention to capitalization when writing JavaScript code.

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