How Can I Replace a Character at a Specific Index in a JavaScript String?

Replacing Characters in JavaScript Strings by Index

When working with strings in JavaScript, it can be necessary to replace a character at a specific index. Unfortunately, JavaScript strings are immutable, meaning you cannot directly modify them.

To address this, you can utilize the following approach:

Creating a Custom replaceAt() Function

Define the replaceAt() function to facilitate character replacement at a specified index:

String.prototype.replaceAt = function(index, replacement) {
    return this.substring(0, index) + replacement + this.substring(index + replacement.length);
};

Usage

Once the replaceAt() function is defined, you can utilize it to replace characters in a string:

var str = "hello world";
alert(str.replaceAt(2, "!!")); // He!!o World

In this example, the character at index 2 (the third character) is replaced with "!!". The alert() function displays the updated string.

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