replace questions

`String.prototype.replace` replaces the first occurrence of a substring or pattern (regular expression) with a new substring. To replace all occurrences, a global regular expression must be used. 

const str = 'hello world';
const newStr = str.replace('world', 'JavaScript');
console.log(newStr); // 'hello JavaScript'

The `str_replace()` function in PHP is used to replace all occurrences of a search string with a replacement string within a given string. For example: `str_replace('world', 'everyone', 'Hello world');` will return `'Hello everyone'`. It can also work with arrays, replacing multiple values at once. This function is useful for text manipulation and cleaning up data.