How to use indexOf() and slice() methods In Javascript

Using the replace() method with regular expression

The indexOf() method finds the index of the first occurrence of the substring.
If the index is greater than or equal to 0 (found a match), it slices the string before and after the match and inserts the replacement.
It recursively calls itself to keep replacing all other matches.
It returns the final string after replacing all matches.

Example: The below code will explain the use of the indexOf() and slice() methods to replace all occurences of a substring.

Javascript

function replaceAll(str, substring, replacement) {
    let index = str.indexOf(substring);
    if (index >= 0) {
        str =
            str.slice(0, index) + replacement + 
            str.slice(index + substring.length);
        str = replaceAll(str, substring, replacement);
    }
    return str;
}
const str = "GeeksforGEEKS";
const subStr = "GEEKS";
const replacement = "Geeks";
console.log("Before replacement: ", str)
let finalResult = 
    replaceAll(str, subStr, replacement);
console.log("After Replacement: ", finalResult);

Output

Before replacement:  GeeksforGEEKS
After Replacement:  w3wiki

Replace all Occurrences of a Substring in a String in JavaScript

In Javascript, a string is a sequence of characters represented with quotation marks. We are given a string and we need to replace all occurrences of a substring from the given string.