Loop through an object of objects with arrays as values

Question

So I have an object like this:

{
  "apples": [
    "one",
    "two"
  ],
  "oranges": [
    "three",
    "four"
  ]
}

How do I look through this object and find four for example? Something like:

for (var i=0; i < obj.length; i++) {
  for (var y=0; y <obj.childObj.length; y++ {
    obj.childObj[i] === 'four' ? return : null;
  }
}

Or is there a better way to structure this data?

Your code is wrong. return cannot be used like that. what is your requirement. — Rajaprabhu Aravindasamy
– Rajaprabhu Aravindasamy, Commented Apr 13, 2016 at 9:48
it depends on the purpose. if you always search for four, then an object with a key four would make sense. — Nina Scholz
– Nina Scholz, Commented Apr 13, 2016 at 9:49
Don't use same variable in nested loops for iteration in your case i; — itzmukeshy7
– itzmukeshy7, Commented Apr 13, 2016 at 9:51
Structure as you want (if you are looking for values that are not unique and good enough to be used as hashmap keys), you are going through all the elements one by one. — Mike B
– Mike B, Commented Apr 13, 2016 at 9:53

Aditya · Accepted Answer · 2016-04-13 09:55:41Z

2

for(var x in obj)
 if(obj.hasOwnProperty(x)) {
  for(var y in obj[x])
   if(obj[x].hasOwnProperty(y)) {
    obj[x][y] === 'four' ? doSomething() : doSomethingElse();
   }
  }

EDIT : Improvement as suggested by Matthew Herbst

edited Apr 13, 2016 at 9:55

answered Apr 13, 2016 at 9:49

Aditya

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6 Comments

j_d Over a year ago

Looks good initially. Is this the most efficient way to store and retrieve multi-dimensional information like this though?

Matthew Herbst Over a year ago

Make sure to also use obj.hasOwnProperty(x) and obj[x].hasOwnProperty(y)

Aditya Over a year ago

I'm not aware of any other way which could give you a significant performance boost over this one.

j_d Over a year ago

What is the benefit of hasOwnProperty?

Tushar Over a year ago

@JohnDoe It'll check only for the own properties and not for the inherited properties. See hasOwnProperty Also see this SO post

|

martin · Accepted Answer · 2016-04-13 09:52:15Z

0

You can use for (x in y) statemment:

var data = {
  "apples": [
    "one",
    "two"
  ],
  "oranges": [
    "three",
    "four"
  ]
};

for (var key in data) {
    var obj = data[key];
    for (var i=0; i <obj.length; i++) {
        // obj[i] === 'four' ? return : null;
        console.log(obj[i]);
    }
}

This will print:

one
two
three
four

answered Apr 13, 2016 at 9:52

martin

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Comments

gurvinder372 · Accepted Answer · 2016-04-13 09:54:00Z

0

If you want to find out if this object has four somewhere then

var isFourAvailable = Object.keys(obj).filter(function(val){ return obj[val].indexOf("four") != -1 }).length > 0;

Making it more generic

function findX(x)
{
   return Object.keys(obj).filter(function(val){ return obj[val].indexOf(x) != -1 }).length > 0;
}

answered Apr 13, 2016 at 9:54

gurvinder372

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Comments

itzmukeshy7 · Accepted Answer · 2016-04-13 09:55:14Z

0

Try this ;)

Modified your code;

for (var i = 0; i < obj.length; i++) {
  for (var y = 0; y < obj[i].length; y++ {
    if(obj[i][y] === 'four'){
      console.log("It's four");
    }
  }
}

answered Apr 13, 2016 at 9:55

itzmukeshy7

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Comments

Rohit Agre · Accepted Answer · 2016-04-13 09:56:36Z

0

You can use indexOf

   var x={
      "apples": [
        "one",
        "two"
      ],
      "oranges": [
        "three",
        "four"
      ]
    }
    for (var e in x) {
      if (x[e].indexOf("four") > -1)
        console.log("found Four");
    }

answered Apr 13, 2016 at 9:56

Rohit Agre

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