Need help understanding how arrays work in javascript for objects

Question

I am having trouble understanding how arrays work in javascript.

Lets say I have an object, car

car = {
moving: false,
wheels: 4
};

Lets say I want to create an array now, of 5 of these cars. How would you do that? I would want to use a for loop to create them, but I have read many pages on js arrays such as http://www.w3schools.com/js/js_arrays.asp and I am still stumped.

I tried doing

carArray = [];
for(int i=0; i < 5; i++)
{
carArray.push(car);
}

However, when the program runs, there is only one car, not 5, and it is at the last entry of carArray.

When arrays and objects are assigned, it assigns a reference to the object, it doesn't make a copy. — Barmar, Dec 25 '14 at 22:21
http://stackoverflow.com/questions/13104494/does-javascript-pass-by-reference — adeneo, Dec 25 '14 at 22:23
In this particular case, you have a typo: `int` should be `var` since JavaScript does not have type declaration. — Kevin Ji, Dec 25 '14 at 22:26
You can create a prototype of car, so you can create 5 different car with new car(). http://www.w3schools.com/js/js_object_prototypes.asp — cesare, Dec 25 '14 at 22:27

score 0 · Accepted Answer · answered Dec 25 '14 at 22:27

0

The word int should be removed. Then the code should work.

carArray = [];
for (i = 0; i < 5; i++) {
  car = {
    moving: false,
    wheels: 4
  };
  carArray.push(car);
}

answered Dec 25 '14 at 22:27

Ian Hazzard

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Okay, thank you. I thought you were only supposed to use the declaration once, not in a for loop like that. Thank you! – qwerty54 Dec 25 '14 at 22:36
You can do it either way, actually. Please accept my answer if it works for you. @qwerty54 – Ian Hazzard Dec 25 '14 at 22:37

Need help understanding how arrays work in javascript for objects

1 Answers1