javascript: how to remove data from array

Question

From below code i tried removing data from array. Unfortunately Its not removing data from my array i.e ary , See if you can help me with this challange

var ary = [{"Force":"Force Converter"},{"Power":"Power Converter"}];

 function removeFav(n,v){ 
       var index = ary.indexOf(n);
       alert(index);
       if (index > -1) {
           ary.splice(index, 1);
        }
         alert("New updated Array:"+ary);
   }

Calling to remove as

removeFav("Power","Power Converter");  // this calls the above method

Why does your method take a v argument that it never uses? — Ian Kemp - SO dead by AI greed
– Ian Kemp - SO dead by AI greed, Commented Apr 7, 2015 at 22:09
as written, you need to pass the object in the array, not a string describing the object. — dandavis
– dandavis, Commented Apr 7, 2015 at 22:10
@IanKemp thats not a problem. This code is part of my huge application. Keeping v in there for now does not makes diffrence — Dan
– Dan, Commented Apr 7, 2015 at 22:11
like removeFav(ary[0]), which is kinda not very helpful really... — dandavis
– dandavis, Commented Apr 7, 2015 at 22:14

Legends · Accepted Answer · 2015-04-08 20:53:25Z

1

Your contains function is perfect. This should work for you, just use the name directly as property

function setFavorite(name, value){
 alert(contains(ary, value));

    var obj = {}; 
    obj.name = value; 
    alert(obj.name);
    ary.push(obj);
    alert(contains(ary, obj));

answered Apr 8, 2015 at 20:53

Legends

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6 Comments

Dan Over a year ago

thanks for your time. i do want to add it in the array , if already exists, here we are writing the contains alert after` ary.push..`

Dan Over a year ago

+ One given .. ...becoz i already accepted answer for this question yesterday

Legends Over a year ago

Donkey Donkey, two many errors, make yourself comfortable with javascript first, wait I will change the script ..... aaaaa

Dan Over a year ago

Hi, jsfiddle.net/pewn1d4m/12 still struggling, its not working as we expected

Legends Over a year ago

Did you take a look at the demo in the answer below: I changed the code a bit, so you only have to pass the property to the Contains function. jsbin.com/cayiyo/2

|

Legends · Accepted Answer · 2015-04-08 23:40:12Z

1

Note: browser support for indexOf is limited, it is not supported in IE7-8.

Here is a demo Demo and below you can find the code again.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <script>

        localStorage.clear();

        var ary = [];
        ary.push({ "Force": "Force Converter" })
        ary.push({ "Power": "Power Converter" });

        function contains(arr, k) {
            var doesContain = false;
            for (var i = 0, length = arr.length; i < length; i++) {
                var item = arr[i];
                if (item.hasOwnProperty(k)) {
                    doesContain = true;
                    break;
                }
            }
            return doesContain;
        }

        if (localStorage.getItem("testObject") != null) {
            alert("localstorage has item testobject");
            //Parse the retrieved value into an array
            ary = JSON.parse(localStorage.getItem('testObject'));
        }

        function setFavorite(k, v) {

            var obj = {};
            obj[k] = v;

            var hasItem = contains(ary, k);

            if (!hasItem) {
                ary.push(obj);
                // Put the object into storage
                localStorage.setItem('testObject', JSON.stringify(ary));
            }


            // Retrieve the object from storage
            var retrievedObject = localStorage.getItem('testObject');

            // Parse the retrieved value into an array
            var retrievedArray = JSON.parse(retrievedObject);

            // clear the ouput first
            $("#fab-id").html("");
            //iterate over the array which contains key-value pairs
            for (var i = 0; i < retrievedArray.length; i++) {
                var item = retrievedArray[i];

                var key = Object.keys(item)[0];
                var value = item[key];

                //----------BELOW CODE DOES NOT WORK PROPERLY----   
                $("#fab-id").append('<a>' + value + '</a><br/>');

            }
        }

    </script>
</head>
<body>
    <button id="btn">Click me!</button>
    <button id="btn2">Add another item!</button>

    <div id="fab-id"></div>

    <script>
        //adding a simple click event handler
        document.getElementById("btn").addEventListener("click", function () {
            //setFavorite("Power", "Power Converter");
            //setFavorite("Power", "Power Converter");
            setFavorite("propA", "X");
        });

        document.getElementById("btn2").addEventListener("click", function () {
            //setFavorite("Power", "Power Converter");
            //setFavorite("Power", "Power Converter");
            setFavorite("xyz", "blabal");
        });
    </script>

</body>
</html>

edited Apr 8, 2015 at 23:40

answered Apr 7, 2015 at 22:17

Legends

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11 Comments

Omar Elawady Over a year ago

if i declare ary like this: var ary = [{"Force":"Force Converter"},{"Power":"bar"}]; and call the function: removeFav("Power","Power Converter"); it will remove it. your condition should be if(obj.hasOwnProperty(n) && obj[n]===v)

Dan Over a year ago

hasOwnProperty means?

Legends Over a year ago

checks if the object has that property

Dan Over a year ago

@Legends what OMAR ELAWADY is saying in coment?

Legends Over a year ago

@Ashutosh ask him ;-)

|

Ian Kemp - SO dead by AI greed · Accepted Answer · 2015-04-07 22:24:32Z

0

Your code is essentially calling ary.indexOf("Power"). But there is no element in ary with the index Power, hence why the call always fails. In fact, Array.indexOf() won't work for your scenario because it only works on simple types, not complex objects.

What you need to do is check for an object with the specified key in that array, and remove said object if it's found. For this you use the Object.hasOwnProperty()method:

function removeFav(key) { 
  for (var i = 0; i < ary.length; i ++) {
    // if the current array item has a property
    // that matches the specified one, remove that item
    if (ary[i].hasOwnProperty(key)){
      ary.splice(i, 1);
      return;
    }  
  }
}

answered Apr 7, 2015 at 22:24

Ian Kemp - SO dead by AI greed

1

3 Comments

Ian Kemp - SO dead by AI greed Over a year ago

@Ashutosh correct, I just prefer to use variable names that make code more readable.

Dan Over a year ago

Thank you for ur explanation. And after this if i do localStorage.setItem('testObject', JSON.stringify(ary)); then it will update new array ,right?

Dan Over a year ago

HI, I got new problem, How can i make array to accept only unique item ? i wrote a boolen method here to check but its not working, can you check this here plz jsfiddle.net/pewn1d4m/9

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