1

i want to push à value in array , but not at the end, not at the start, at the first empty index

Show the code exemple:

var test=new Array();
test[0]="Lionel";
test[2]="Jhon";
test.push("Cloé");

result:

[ 'Lionel', <1 empty item>, 'Jhon', 'Cloé' ]

And i need to have Cloé just after Lionel Thanks

Edit this is different to insert in specific index, because i can't know the number of empty index, this is slot system . And i just wanna know if we have native solution ?.

Lionel R
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  • `test[1] = 'Cloe'?` – Manav Sep 08 '17 at 12:18
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    `push` simply does `test[test.length] = value`. If you have a different definition of what it should do you need to implement it yourself with a loop. – deceze Sep 08 '17 at 12:19
  • Check this out https://stackoverflow.com/questions/586182/how-to-insert-an-item-into-an-array-at-a-specific-index – RaidenF Sep 08 '17 at 12:21
  • Possible duplicate of [How to insert an item into an array at a specific index?](https://stackoverflow.com/questions/586182/how-to-insert-an-item-into-an-array-at-a-specific-index) – RaidenF Sep 08 '17 at 12:21
  • is the unset index undefined, null or <1 empty item>? – Oliver Sep 08 '17 at 12:21

6 Answers6

2

You could search for a sparse index and return this index for inserting a value.

function getIndex(array) {
    var last = 0;
    array.some(function (_, i) {
        return last < i || !++last;
    });
    return last;
}

var test = ["Lionel", , "Jhon"];

test[getIndex(test)] = "Cloé";

console.log(test);
Nina Scholz
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1

You could write a simple function to look for a gap with undefined as the value and place the new value if if found - otherwise just push to the end of the array

function insertFirstGap(array, value){
    for(var i = 0;i<array.length;i++){
        if(array[i] === undefined){
            array[i] = value; 
            return; 
        }
    }
    array.push(value);

}

Live example below:

var test=new Array();
test[0]="Lionel";
test[2]="Jhon";

insertFirstGap(test,"Cloé");

console.log(test, test.length);

function insertFirstGap(array, value){
    for(var i = 0;i<array.length;i++){
        if(array[i] === undefined){
            array[i] = value;  
            return;
        }
    }
    array.push(value);
     
}
Jamiec
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  • Hello, this is the same code i write, but i search a native function , thanks you have understand my problem, and your solution is correct, now i know we don't have native solution ! – Lionel R Sep 08 '17 at 12:31
  • if you have a value of `undefined`, i gets overwritten. – Nina Scholz Sep 08 '17 at 12:42
  • @NinaScholz I thought that was the *requirement*. If its not ive misunderstood. – Jamiec Sep 08 '17 at 12:53
  • maybe we define *"empty"* different. for me, an empty element is only possible to check with `in` operator (--> `false`) or with an iteration with a method, where the sparse items are not visited. – Nina Scholz Sep 08 '17 at 12:59
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    @NinaScholz yeah you have a valid point. I suspect `undefined` will probably satisfy this person's requirement. But you are fo course logically correct. – Jamiec Sep 08 '17 at 13:26
0

you can do it in the following way

var test=new Array();
test[0]="Lionel";
test[2]="Jhon";

let x = test.length;
Object.keys(test).forEach(function(element, idx){
    if(element != idx){
        x = (x==test.length ? idx: x);
    }
})
test[x] = "Cloe"
console.log(test);
marvel308
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0

Solution 1

If you know which index you want to apply the value to, use test[x] = "Cloe".

Solution 2

If you want to apply the value to the first empty item, use a for loop that goes through every item in the array until it finds one that's empty.

test = ["Lionel", "", "Jhon", ""];

for (var i = 0; i < test.length; i++) {
  if (!test[i]) {
    test[i] = "Cloe";
    break;
  }
}

console.log(test)

EDIT:

If you only want to use native functions. Use splice and indexOf. 

test = ["Lionel", "", "Jhon", ""];

test.splice(test.indexOf(""), 1, "Cloe")

console.log(test)

test.splice(index, 1, item) inserts item into test at the specified index. indexOf("") search for an array with no value in it and return its position.

  • i don't know the index, and i search if we have native solution. – Lionel R Sep 08 '17 at 12:50
  • @LionelR If you don't know the index, then try **Solution 2**. Also, what do you mean by "native solution"? –  Sep 08 '17 at 12:52
  • Native solution is function include in es6 . push is native for exemple , this is not a function you must write. – Lionel R Sep 08 '17 at 13:03
  • @LionelR Then you can use the `splice` function, `test.splice(test.indexOf(""), 0, item)`, to insert `item` into `test` at the index where "" is located. –  Sep 08 '17 at 13:26
  • if i have "" entry on my array ? – Lionel R Sep 08 '17 at 13:31
  • @LionelR No, it means `empty`. Thus, an item with no value in it. –  Sep 08 '17 at 13:33
  • @LionelR Sorry, I meant `test.splice(test.indexOf(""), 1, item)`. Please see edit. –  Sep 08 '17 at 13:40
0

Ok, we don't have native solution, this is my solution with code, my final objective is slot systeme :

 FindValidSocket(Type){
    let count=0;
    while (count!==this.Max[Type]){
        if(typeof(this.traitement[Type][count])==="undefined"){
            return count;
        }else{
            count++;
        }
    }
    return false;
}

Thanks all for your response

Lionel R
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-1
function insertIntoFirstEmpty(val, arr) {
   for(var i = 0;i<arr.length;i++) {
      if(typeof arr[i] === 'undefined')
      {
         arr[i] = val;
         return;
      }
   }
   arr.push(val);
}
RaV
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