javascript - making a function that pulls all number from an array divisible by 3 - Stack Overflow

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var array = [3, 4, 6, 5, 9, 10, 21];

var divThree = [];

var loveTheThrees = function (array) {
  for (i = 0; i = array.length; i++) {
    if (array[i] % 3 === 0) {
      amount.push(divThree[i]);
    }
  }
}

I am just learning Javascript and having a bit of trouble with this function. I can feel im close but cant figure out what im doing wrong.

var array = [3, 4, 6, 5, 9, 10, 21];

var divThree = [];

var loveTheThrees = function (array) {
  for (i = 0; i = array.length; i++) {
    if (array[i] % 3 === 0) {
      amount.push(divThree[i]);
    }
  }
}

I am just learning Javascript and having a bit of trouble with this function. I can feel im close but cant figure out what im doing wrong.

• javascript
• arrays
• for-loop

Share Improve this question Follow asked Aug 1, 2016 at 18:53 Josh-HarrisJosh-Harris 3133 bronze badges 2

• Note: you should write for (var i = 0 instead of for (i = 0 – gcampbell Commented Aug 1, 2016 at 18:55
• what is your error? What state are you trying to hit now? – joncodo Commented Aug 1, 2016 at 19:00

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6 Answers 6

Sorted by: Reset to default 8

Just use filter()

divThree = array.filter(x => x%3 === 0);

There are different ways of going about it (as evidenced by the other answers here), but the bug in the code you posted is that the i = array.length is resetting the value of i. You'll want to use a < instead. You also need to push into the proper array.

var array = [3, 4, 6, 5, 9, 10, 21];

var divThree = [];

var loveTheThrees = function (array) {
  for (i = 0; i < array.length; i++) {
    if (array[i] % 3 === 0) {
      divThree.push(array[i]);
    }
  }
}

You can use .filter of array

var array = [3, 4, 6, 5, 9, 10, 21];

var output = array.filter(function(num){
  return num%3 ==0
});
console.log(output);

In your code you are assign i = array.length instead of a condition, so your loop is infinite. You need to change = into the <. And also push into the dimThree not to amount.

 var array = [3, 4, 6, 5, 9, 10, 21];

    var divThree = [];
    
    var loveTheThrees = function (array) {
      for (i = 0; i < array.length; i++) {
        if (array[i] % 3 === 0) {
          divThree.push(array[i]);
        }
      }
    }

loveTheThrees(array);
divThree.forEach(x => console.log(x));

Or use filter() function

 var array = [3, 4, 6, 5, 9, 10, 21];
    var divThree = [];
    
    divThree = array.filter(x => x % 3 === 0);

divThree.forEach(x => console.log(x));

you will have to push the right value:

divThree.push(array[i]);

and: you can implement a for loop like:

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

or

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

You first need to correct the for-loop condition from i=array.length to i < array.length. But even more important in this case - you need to consider the following: You want to add/push the values that are divisible by 3 into an array called divThree - so the correct syntax is <destination-array>.push(<value-to-push>). So in this case, if the current value array[i] is divisible by three you want to push it into the array called divThree so you do something like this:

for (i = 0; i < array.length; i++) {
    if (array[i] % 3 === 0) {
      //here we push array[i] into the array because it is divisible my 3
      divThree.push(array[i]);
    }
  }

As you progress in your Javascript, you will find that in this case, it is easier to use lodash (for NodeJS apps) as it provides very nice convenience functions of these kinds of things.

I hope this helps.

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