js array minus

gistfile1.js

// console.log(itemUsedCurrencys);
// console.log(itemOriginCurrencys);
var itemOriginCurrencys = ['USD', 'HKD', 'CNY', 'EUD'];
var itemUsedCurrencys = ['USD', 'HKD'];

var i = itemOriginCurrencys.length;

while (i--) {
  var index =  itemUsedCurrencys.indexOf( itemOriginCurrencys[i] )
  // console.log('check : '+itemOriginCurrencys[i] + " pos: "+ index);

  if (index >= 0) {
      itemOriginCurrencys.splice(i, 1);
  }
}

// itemOriginCurrencys = ['CNY', 'EUD'];