Dynamic property names for loop of object Javascript

Question

In Javascript is there a clever way to loop through the names of properties in objects in an array?

I have objects with several properties including guest1 to guest100. In addition to the loop below I'd like another one that would loop through the guestx properties without having to write it out long hand. It's going to be a very long list if I have to write the code below to results[i].guest100, that is going to be some ugly looking code.

for (var i = 0; i < results.length; i++) {
if (results[i].guest1 != "") {
    Do something;
}
if (results[i].guest2 != "") {
    Do something;
}
if (results[i].guest3 != "") {
    Do something;
}
etcetera...
}

gdoron · Accepted Answer · 2012-05-12 18:52:15Z

5

Try this:

for (var i = 0; i < results.length; i++) {
    for (var j=0; j <= 100; j++){
        if (results[i]["guest" + j] != "") {
            Do something;
        }
    }
}

answered May 12, 2012 at 18:52

gdoron

151k59 gold badges302 silver badges376 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Michael Berkowski · Accepted Answer · 2012-05-12 19:01:14Z

3

Access properties by constructing string names in the [] object property syntax:

// inside your results[i] loop....
for (var x=1; x<=100; x++) {
  // verify with .hasOwnProperty() that the guestn property exists
  if (results[i].hasOwnProperty("guest" + x) {
     // JS object properties can be accessed as arbitrary strings with []
     // Do something with results[i]["guest" + x]
     console.log(results[i]["guest" + x]);
  }
}

edited May 12, 2012 at 19:01

answered May 12, 2012 at 18:50

Michael Berkowski

271k47 gold badges450 silver badges395 bronze badges

1 Comment

gdoron Over a year ago

It's hard to me to believe that you will ever have a property named guest1\ guest2..., which is not an ownProperty of the object. :)

Sebas · Accepted Answer · 2012-05-12 18:51:17Z

2

I think you'll find useful the "in" operator:

if (("guest" + i) in results[i]) { /*code*/ }

Cheers

answered May 12, 2012 at 18:51

Sebas

21.6k9 gold badges60 silver badges109 bronze badges

Collectives™ on Stack Overflow

Dynamic property names for loop of object Javascript

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related