How to create nested JSON objects dynamically?

Question

I want to create a JSON object words which further contains a list of objects s and e with different values as follows:

words = {
    "a1": { s: 1.5, e: 2 },
    "a2": { s: 2.1, e: 2.4 },
    "a3": { s: 2.5, e: 3 },
    "a4": { s: 3.5, e: 3.8 },
    "a5": { s: 3.9, e: 4.5 },
    "a6": { s: 4.8, e: 5.2 },
    "a7": { s: 5.3, e: 5.3 },
    "a8": { s: 6.5, e: 7 },
    "a9": { s: 7.2, e: 8 },
    "a10": { s: 8.1, e: 8.4 }
};

I need to add these values using a for loop. I have applied the following solution for this:

var words = {};
var xyz = [1.5,2,2.1,2.4,2.5,3,3.5,3.8,3.9,4.5,4.8,5.2,5.3,5.3,6.5,7,7.2,8];
words = '{';
for (var i = 0; i <= 10; i++) {
    if (i == 10)
        var obj = '\"a' + i + '\"'+': { s:' + xyz[i] + ', e:' + xyz[i + 1] + '}';
    else
        var obj = '\"a' + i + '\": { s:' + xyz[i] + ', e:' + xyz[i + 1] + '},';

    words = words + obj;
}
words = words + '}';

$.parseJSON(words);

But this generates an error of:

Uncaught SyntaxError: Unexpected token s**

I am not able to create the object due to this.

raina77ow · Accepted Answer · 2012-12-20 15:26:48Z

4

You don't need to create a JSON string, then parse it with JS: it's far more easily done with this:

var words = {},
    xyz = [1.5,2,2.1,2.4,2.5,3,3.5,3.8,3.9,4.5,4.8,5.2,5.3,5.3,6.5,7,7.2,8];

for (var i = 0, l = xyz.length/2; i < l; i++) {
  words['a' + (i + 1)] = { 
    s: xyz[2*i], 
    e: xyz[2*i + 1] 
  };
}

console.log(words);

Explanation: you go through your source arrays, taking each pair into an object literal and assign it to words object with bracket notation (so that value of 'a' + (i+1) is evaluated as a new key).

edited Dec 20, 2012 at 15:26

answered Dec 20, 2012 at 15:11

raina77ow

107k16 gold badges205 silver badges240 bronze badges

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

Comments

T.J. Crowder · Accepted Answer · 2012-12-20 15:12:15Z

There's basically no reason to create a JSON string in a browser manually, instead create the object and then use JSON.stringify on it. (Most browsers have it by default, if not you can add a shim.) For instance:

var counter;
var words = {};
var xyz = [1.5,2,2.1,2.4,2.5,3,3.5,3.8,3.9,4.5,4.8,5.2,5.3,5.3,6.5,7,7.2,8];
var i;
counter = 0;
for (i = 0; i < xyz.length; i += 2) {
    ++counter;
    words["a" + counter] = {s: xyz[i], e: xyz[i + 1]};
}
console.log("words (before stringify):", words);
words = JSON.stringify(words);
console.log("words (after stringify):", words);

If you're going to create JSON manually, you need to learn and follow its rules. The keys must be in double quotes (so, "s": ... not s: ...), for instance.

Collectives™ on Stack Overflow

How to create nested JSON objects dynamically?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related