Finding field.value in JSON array

Question

var x = [{ a: 1, b: 2}, { a: 11, b: 12}, { a: 31, b: 23}, { a: 51, b: 24}]

how do you find a = 11 ?

for simple arrays one can do x.indexOf('1'); so perhaps the solution should be something like

var a1 = x.indexOf({a: 1});

ofcourse, I want to obtain the entire JSON for which the value matches.

This is not JSON. It's an array of plain objects. Also, I'm pretty sure this is a duplicate. — John Dvorak
– John Dvorak, Commented Oct 21, 2013 at 14:59
JavaScript doesn't have built-in support for object querying like you're expecting. Though, there may be libraries that can add it. But, indexOf() searches with ===, which for Objects requires they be the exact same object; not just similar. — Jonathan Lonowski
– Jonathan Lonowski, Commented Oct 21, 2013 at 15:01
@JonathanLonowski thanks. thats what i wanted to know. I can now look at both recommended solution of writing code or using underscore lib. — Sangram Singh
– Sangram Singh, Commented Oct 21, 2013 at 15:02

Nasser Torabzade · Accepted Answer · 2013-10-21 15:04:15Z

4

you can do it with a simple function, no third party modules needed:

var x = [{ a: 1, b: 2}, { a: 11, b: 12}, { a: 31, b: 23}, { a: 51, b: 24}];

function getIndexOf(value){
    for(var i=0; i<x.lengh; i++){
        if(x[i].a == value)
            return i;
    }
}

alert(getIndexOf(value)); // output is: 1

answered Oct 21, 2013 at 15:04

Nasser Torabzade

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PSL · Accepted Answer · 2013-10-21 15:02:45Z

2

You can use Array.Filter with shim support on older browsers.

var x = [{
    a: 1,
    b: 2
}, {
    a: 11,
    b: 12
}, {
    a: 31,
    b: 23
}, {
    a: 51,
    b: 24
}],
tocomp = 11;
var res = x.filter(function (ob) { 
    return ob.a === tocomp;
});

Result will be array of object that matches the condition.

Fiddle

And if you just care for single match and get back the matched object just use a for loop.

var x = [{
    a: 1,
    b: 2
}, {
    a: 11,
    b: 12
}, {
    a: 31,
    b: 23
}, {
    a: 51,
    b: 24
}],
tocomp = 11, i, match;
for (i=0, l=x.length; i<l; i++){
    if(x[i].a === tocomp){
        match = x[i];
        break; //break after finding the match
    }
}

answered Oct 21, 2013 at 15:02

PSL

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Comments

Sachin · Accepted Answer · 2013-10-21 15:00:19Z

1

Simply iterate over the array to get the value.

for(var i = 0;i < x.length; i++){
   alert(x[i].a);
}

JsFiddle

answered Oct 21, 2013 at 15:00

Sachin

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Comments

user1934722 · Accepted Answer · 2013-10-21 15:00:25Z

1

You can use native js or you can use underscoreJS lib. UnderscoreJS

answered Oct 21, 2013 at 15:00

user1934722

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