Javascript loop array in realtime

Question

is there a way to loop an array in "real time" in Javascript or using JQuery? What I mean is to create a loop that reads the array content without caching it before starting the loop, for example if I do this.

var array = [{'hi':0},{'how':1},{'are':2},{'you':3}];

for(var i=0;i < array.length;i++){
  console.log(i);
  if(i == 2){
    array.push({'?':4});
  }
}
console.log(array);

The loop will output only 4 values but it already has 5 values before finishing the loop

I would like to also loop the new values inserted while the loop is running.

For more clarification, I need to do this because I am building a web app that creates a queue before submitting data to the server, a loop submits the data in the array but this array can also be updated in the process by other functions

Thanks!

@AnkitAgarwal his question is clear to me - he wants to mutate the array during the loop, and wants the loop to keep going while insertions are made to the array — Abdul Ahmad
– Abdul Ahmad, Commented Aug 17, 2018 at 13:46
@duxfox-- yes, but he said that it was logging just 4 values, but it's not true, the loop is logging the entire array including the value added inside the loop, so 5 values — Calvin Nunes
– Calvin Nunes, Commented Aug 17, 2018 at 13:47
Are you forgetting that index starts at zero and 4 is actually the 5th iteration? — epascarello
– epascarello, Commented Aug 17, 2018 at 13:47
Add more logging details to your code and you will see the index you added at the end of the loop. console.log(i, JSON.stringify(array[i])); — epascarello
– epascarello, Commented Aug 17, 2018 at 13:50

Jeremy Thille · Accepted Answer · 2018-08-17 13:50:18Z

2

Your code works as you want. It works because at each iteration, you evaluate i against array.length, so even if the length changes during one iteration, the loop will adapt accordingly.

It would not work if you used :

for(var i=0, j=array.length; i<j; i++){

because in this case, the length is stored in j, and then j doesn't change, regardless of what happends in the loop.

answered Aug 17, 2018 at 13:50

Jeremy Thille

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