JSFiddle - React, Tailwind, and code Playground

by konglie

HTML

<h1 id='res'>
</h1>

JavaScript

var json = [{"1":3},{"2":2},{"5":6},{"12":1}];
var cariID = 5;

function findIndex(id) {
  var item;
  for (var index in json) {
    item = json[index];
    if(Object.keys(item)[0] == id){
    	return index;
    }
  }
  
  return -1;
}

document.getElementById('res').innerHTML = cariID + ' ada di index ' + findIndex(cariID);