How to usea Loop with substring() and indexOf() Methods in Javascript

Method 5: Using ES6’s findIndex() method

This method involves iterating through the string and using the substring method to compare slices of the original string with the target substring.

Example: Here is an example to find the index of the first occurrence of a substring in a string using a loop with the substring() and indexOf() methods.

JavaScript

// Example string 
const originalString = "This is a sample string";

// Target substring 
const targetSubstring = "sample";

// Finding the index of the first occurrence of the target substring using a loop
let index = -1;
for (let i = 0; i <= originalString.length - targetSubstring.length; i++) {
    if (originalString.substring(i, i + targetSubstring.length) === targetSubstring) {
        index = i;
        break;
    }
}

console.log("Index of the first occurrence:", index);

Output

Index of the first occurrence: 10

JavaScript Program to find the Index of the First Occurrence of a Substring in a String

In this article, we will find the index of the first occurrence of a substring in a string using JavaScript.

An essential task in JavaScript programming is searching for substrings within a string. Finding the index of the first occurrence of a substring is a typical necessity, whether you are constructing a website, working with data processing, or simply altering the text.

How to usea Loop with substring() and indexOf() Methods in Javascript

JavaScript Program to find the Index of the First Occurrence of a Substring in a String

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