JSFiddle - React, Tailwind, and code Playground

by shojikun

HTML

<input class='test' name="product[0][category]">

JavaScript

$('.test').find('input').attr('name', function(){ return '[]'})
var result = test.replace(/\[(\d+)\]/, function(str,p1){
    return '[' + (parseInt(p1,10)+1) + ']';
});
alert(result);