CODEWITHSUNDEEP
javascriptfirefoxfor-loop
kevinius
kevinius

Reputation: 4618

For each...in loop not running: syntax error missing (

This for each...in loop is not running, allthough it's a direct copy from the mozilla Javascript guide about the for each...in statement. 

var sum = 0;
var obj = {prop1: 5, prop2: 13, prop3: 8};
for each (var item in obj) {
  sum += item;

}

alert(sum); // prints "26", which is 5+13+8

jsFiddle: http://jsfiddle.net/4fVSB/1/

I'm getting this error:

SyntaxError: missing ( after for for each (var item in obj) {

Could this have something to do with my javascript version. For some reason my FF has javascript version 1.5 while i do have FF 24.0 installed. Shouldn't this version of FF have the latest javascript version?

Fiddle to see what version of js i have: http://jsfiddle.net/Ac6CT/

Thx,

Upvotes: 1

Views: 1864

Answers (4)

Moazzam Khan
Moazzam Khan

Reputation: 3170

The for each...in statement is deprecated as the part of ECMA-357 (E4X) standard. E4X will be disabled by default and removed in the future, but for each...in will not be disabled and removed because of backward compatibility considerations. Consider using for...of instead.

for each...in

Upvotes: 0

MatthewMartin
MatthewMartin

Reputation: 33173

From this page it appears that "for each" (for-space-each) is deprecated. So the engine is looking for a ( after for, e.g. for(

I would recommend using the underscore library _.each or the equivalent in jquery, e.g. $(..).each()

Upvotes: 0

Vlad Miller
Vlad Miller

Reputation: 2279

Just use regular for loop to avoid any consequences

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

The for each...in statement is deprecated as the part of ECMA-357 (E4X) standard. E4X will be disabled by default and removed in the future, but for each...in will not be disabled and removed because of backward compatibility considerations. Consider using for...of instead. (Please refer to bug 791343.)

Upvotes: 2

Michael Kunst
Michael Kunst

Reputation: 2988

The right syntax is just for(var item in obj), without the each. And then in the actual loop you have to acces the numeric value (i.e. 5, 13 etc.) with obj[item].

Your code should look like this at the end:

var sum = 0;
var obj = {prop1: 5, prop2: 13, prop3: 8};
for(var item in obj) {
  if(obj.hasOwnProperty(item)){
    sum += obj[item];
  }
}

alert(sum);

The hasOwnProperty function makes sure you don't accidentaly loop over inherited methods.

Upvotes: 4

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