I need to perhaps write a function that just outputs the index of an object inside an array, obviously, using $.inArray returns this just fine in the example below.

array = ['one', 'two', 'three'];

$.inArray('one', array) // 0

With a more elaborate array, How can I find the index of the objects nested within?

array = [
    {
        name: 'One', // index??
        data: {
            title: 'Title One',
            content: 'Content One'
        }
    },
    {
        name: 'Two',
        data: {
            title: 'Title Two',
            content: 'Content Two'
        }
    },
    {
        name: 'Three',
        data: {
            title: 'Title Three',
            content: 'Content Three'
        }
    }
];

I've heard of the $.grep() method, indexOf() .. not sure which one to use to just return an integer of the index the object is in

I need to perhaps write a function that just outputs the index of an object inside an array, obviously, using $.inArray returns this just fine in the example below.

array = ['one', 'two', 'three'];

$.inArray('one', array) // 0

With a more elaborate array, How can I find the index of the objects nested within?

array = [
    {
        name: 'One', // index??
        data: {
            title: 'Title One',
            content: 'Content One'
        }
    },
    {
        name: 'Two',
        data: {
            title: 'Title Two',
            content: 'Content Two'
        }
    },
    {
        name: 'Three',
        data: {
            title: 'Title Three',
            content: 'Content Three'
        }
    }
];

I've heard of the $.grep() method, indexOf() .. not sure which one to use to just return an integer of the index the object is in

• javascript
• arrays
• indexing

Share Improve this question Follow asked Jul 26, 2012 at 2:01 Jeff VossJeff Voss 3,6951010 gold badges4949 silver badges7272 bronze badges 1

• None of those functions handle multi-dimensional arrays. You'll have to roll your own search function. indexof/grep can be used at each level of the array, but moving between levels is up to you. – Marc B Commented Jul 26, 2012 at 2:04

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3 Answers 3

Sorted by: Reset to default 5

You don't need a pre-written function, just iterate over your array and pare the name property:

function findValue(array, nameWeAreLookingFor) {
    for(var i = 0; i<array.length; i++) {
        if(array[i].name === nameWeAreLookingFor) return i;
    }
    return -1;
}

No built in functions.. but it's easy to write all flavours of your own. And as an exercise you can also use them to extend jQuery,

var array = [{
    name: 'One',
    // index??
    data: {
        title: 'Title One',
        content: 'Content One'
    }},
{
    name: 'Two',
    data: {
        title: 'Title Two',
        content: 'Content Two'
    }},
{
    name: 'Three',
    data: {
        title: 'Title Three',
        content: 'Content Three'
    }}];

function findByName(name) {
    var index;
    $(array).each(function(i, e) {
        if (e.name && e.name == name) {
            index = i;
            return false;
        }
    });
    return index;
}
console.log(findByName("One")); // prints 0

// and now even better ... find by any property


function findByProperty(objects, prop, value) {
    var index;
    $(objects).each(function(i, e) {
        if (e[prop] && e[prop] == value) {
            index = i;
            return false;
        }
    });
    return index;
}

// usage
var index = findByProperty(array, "name", "One");
console.log(index); // prints 0
index = findByProperty(array, "name", "Three");
console.log(index); // prints 2
// and even more powerful


function findByFilter(objects, filter) {
    var index;
    $(objects).each(function(i, e) {
        if (filter(i, e)) {
            index = i;
            return false;
        }
    });
    return index;
}

index = findByFilter(array,function(i,e){ return e.data.title=="Title Two"; });
console.log(index); // prints 1

You can use the name property as index.

Try this code:

var indexOfObj = function(array,objName){
    var len = array.length;
    while(--len>=0 && array[len].name!==objName);
    return len;
}

This function will return -1 if the obj wasn't found in the array.