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1

I have an array of objects as follows within my server side JS:

[
    {
        "Company": "IBM"
    },
    {
        "Person": "ACORD LOMA"
    },
    {
        "Company": "IBM"
    },
    {
        "Company": "MSFT"
    },
    {
        "Place": "New York"
    }
]

I need to iterate through this structure, detect any duplicates and then create a count of a duplicate is found along side each value.

Both of the values must match to qualify as a duplicate e.g. "Company": "IBM" is not a match for "Company": "MSFT".

I have the options of changing the inbound array of objects if needed. I would like the output to be an object, but am really struggling to get this to work.

EDIT: Here is the code I have so far where processArray is the array as listed above.

var returnObj = {};

    for(var x=0; x < processArray.length; x++){

        //Check if we already have the array item as a key in the return obj
        returnObj[processArray[x]] = returnObj[processArray[x]] || processArray[x].toString();

        // Setup the count field
        returnObj[processArray[x]].count = returnObj[processArray[x]].count || 1;

        // Increment the count
        returnObj[processArray[x]].count = returnObj[processArray[x]].count + 1;

    }
    console.log('====================' + JSON.stringify(returnObj));
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3  
What have you tried? – Frits van Campen May 10 '12 at 19:43
1  
possible duplicate of Remove duplicates from an array of objects in javascript – Royi Namir May 10 '12 at 19:46
2  
Not all such question deserve What have you tried. It is legitimate question not a spam. – Sarfraz May 10 '12 at 19:47
1  
@Sarfraz lol ... you right :)........(ps , what have you tried ?) – Royi Namir May 10 '12 at 19:48
And why should someone else do this work for you? – Travis J May 10 '12 at 19:50
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2 Answers

up vote 8 down vote accepted

For example:

counter = {}

yourArray.forEach(function(obj) {
    var key = JSON.stringify(obj)
    counter[key] = (counter[key] || 0) + 1
})

Docs: Array.forEach, JSON.stringify.

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I don't believe there's a forEach function on arrays. – Elliot Bonneville May 10 '12 at 19:59
2  
@ElliotBonneville: but you do believe in google, don't you – thg435 May 10 '12 at 20:05
Wow, I can't believe I've never heard of that function! I know what I'm doing instead of 8 zillion for loops, now. Thanks! – Elliot Bonneville May 10 '12 at 20:08
@thg435 This is superb! I learnt a lot here, thanks very much. – Ben May 10 '12 at 20:09
@ElliotBonneville: not at all, I added doc links to the post for others who are curious. – thg435 May 10 '12 at 20:11
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up vote 1 down vote 
Object.prototype.equals = function(o){
    for(var key in o)
        if(o.hasOwnProperty(key) && this.hasOwnProperty(key))
            if(this[key] != o[key])
                return false;
    return true;
}
var array = [/*initial array*/],
    newArray = [],
    ok = true;
for(var i=0,l=array.length-1;i<l;i++)
    for(var j=i;j<l+1;j++)
    {
       if(!array[i].equals(array[j]))
           newArray.push(array[i]);
    }
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