How to check if object value in array already exists using jquery

Question

how to check if an object value already in an array exists ? If not push a value

html:

<form>
  <input type="text" id="input" name="input">
  <button type="button" name="save">save</button>
</form>

jquery:

$('document').ready(function(){
    $myData = [];

    $('button[name=save]').on('click', function(){
        var input = $('#input').val();
            $myData.indexOf({'input':input}) === -1 ? $myData.push({'input':input}) : console.log('already exists');
      console.log($myData);
  });   
});

no, just for testing. The whole thing should look like {product:XXXXX, quantity: XXXX}, if the product is already in array just update the quantity if not save the whole object into the array — Greg Ostry
– Greg Ostry, Commented Jul 27, 2017 at 10:57

user3297291 · Accepted Answer · 2017-07-27 10:55:34Z

8

The first thing you should know is that, in javascript:

({ 'input': input} === { 'input': input }) // returns false

=== compares the object reference, not the way the objects look.

That means that indexOf({input: input}) will never return anything else than -1.

You can solve this by using some. some takes a function to compare stuff, so you can write your own "equals" (instead of indexOf using ===).

if ($myData.some(item => item.input === input)) console.log("exists")
else $myData.push({input: input});

answered Jul 27, 2017 at 10:55

user3297291

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2 Comments

Jonas Wilms Over a year ago

Welcome to the privileged users ! ;)

user3297291 Over a year ago

@Jonasw Well spotted! Thanks :)

Arun pandian M · Accepted Answer · 2017-07-27 11:05:07Z

2

try this :

if(myArray.find(x => x.input === input)){
console.log("Exist");
} else{
anotherarray.push({'input':input});
}

The find() method returns a value in the array, if an element in the array satisfies the provided testing function. Otherwise undefined is returned.

If you want to get array of matching elements, use filter() method instead:

myArray.filter(x => x.id === input)

If you want to get array of another property properties, you can do this with map() method:

myArray.filter(x => x.id === input).map(x => x.anotherproperty)

edited Jul 27, 2017 at 11:05

answered Jul 27, 2017 at 10:57

Arun pandian M

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1 Comment

Rory McCrossan Over a year ago

Not sure why this is upvoted; it doesn't work. Aside from the :'' syntax error, filter() always returns an array - even an empty one. Using an array in a condition will always equate to true, hence the else is never hit.

Matt · Accepted Answer · 2017-07-27 10:58:25Z

0

These objects will have two different references so it will always return false. Use .some or .find and do a value comparison of the .input field.

const itemExists = $myData.some(el => el.input === input);
if(itemExists) {
   console.log("Already exsists");
} 
else {
   $myData.push({'input':input})
}

answered Jul 27, 2017 at 10:58

Matt

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Comments

Jonas Wilms · Accepted Answer · 2017-07-27 11:00:22Z

0

Looks like a perfect usecase for a hash table:

var hash={},result=[];

$('button[name=save]').on('click', function(){
    var input = $('#input').val();
    if(hash[input]){
      hash[input].quantity++;
    }else{
      result.push(hash[input]={input,quantity:1});
    }
 });

answered Jul 27, 2017 at 11:00

Jonas Wilms

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Comments

Jahil Khalfe · Accepted Answer · 2017-07-27 11:08:11Z

0

You should just use the includes array method array.includes(some value) and then if it does not include as includes returns a bool you can push. Note this is plain Javascript. Array includes method

let array = [1, 2, 3, 4, 5];
console.log(array)
if (array.includes(2)) {
  array.push(20);
}
console.log(array)

edited Jul 27, 2017 at 11:08

answered Jul 27, 2017 at 10:57

Jahil Khalfe

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Comments

shashank mishra · Accepted Answer · 2017-07-27 11:13:33Z

0

indexOf works well with Strings but to check within an array you cannot simply use it.

Other method could be iterating whole array and check but that would be very costly in terms of time complexity.

So best answer would be to use simple map in such cases. Try below -

$('document').ready(function(){ 
var myData = new Object(); // or var map = {};

$('button[name=save]').on('click', function(){
    var input = $('#input').val(); 
        if(myData[input] != input) 
            myData[input] = input;
        else
          console.log('already exists'); 


});   
});

answered Jul 27, 2017 at 11:13

shashank mishra

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