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javascriptloopsforeachenumerationfor-in-loop

What is the difference between for..in and for each..in in javascript?

What is the difference between for..in and for each..in statements in javascript? Are there subtle difference that I don't know of or is it the same and every browser has a different name for it?

Solution

  • "for each...in" iterates a specified variable over all values of the specified object's properties.

    Example:

    var sum = 0;
var obj = {prop1: 5, prop2: 13, prop3: 8};
for each (var item in obj) {
  sum += item;
}
print(sum); // prints "26", which is 5+13+8

    Source

    "for...in" iterates a specified variable over all properties of an object, in arbitrary order.

    Example:

    function show_props(obj, objName) {
   var result = "";
   for (var i in obj) {
      result += objName + "." + i + " = " + obj[i] + "\n";
   }
   return result;
}

    Source

    Note 03.2013, for each... in loops are deprecated. The 'new' syntax recommended by MDN is for... of.