how to replace a letter in a string javascript code example

Example 1: js replace characters in a string

var str = "Original string!";
var str = str.replace("Original", "New");

Example 2: javascript regex replace

const search = 'duck'
const replaceWith = 'goose';

const result = 'duck duck go'.replaceAll(search, replaceWith);

result; // => 'goose goose go'