Question

How to replace the first occurrence of a substring in a string with JavaScript

Answer 1

function replaceFirst(input, search, replace) {
    const index = input.indexOf(search);

    if (index === -1) return input;

    return input.substring(0, index) + replace + input.substring(index + search.length);
}

const s = "aa bb cc dd ee cc";
const result = replaceFirst(s, "cc", "YY");

console.log(result);

 

/*
run:
  
aa bb YY dd ee cc
     
*/

 

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