invertkeyvalues.js

function invertKeyValues(obj) {
  var inv = {},
      val;
  for(var i in obj) {
    val = obj[i];
    inv[val] = inv[val] || [] ;
    inv[val].push(i);
  }
  return inv;
}

function test() {
  var repeated = invertKeyValues({
    a: 1,
    b: 2,
    c: 3,
    d: 1,
    e: 0,
    f: 2,
    g: 0,
    h: 1
  });
  
  
  for(var j in repeated) {
    if(repeated[j].length>1) {
      console.log("value: '" + j + "' repeats in keys: [" + repeated[j].join(", ") + "]");
    }
  }
  
  
}

Find Duplicate Values in an Object

Given an object with key value pairs, this simple function allows one to find the keys which have duplicated values.