CODEWITHSUNDEEP
javascriptfor-loop
John DellaVecchio
John DellaVecchio

Reputation: 23

Trouble with For loops sumArray

I am having trouble with for loops and I cannot seem to figure this out. I need to add the numbers in an array. The closest I get is I get the loop to print the array 1,2,3 three times with this code

function sumArray(num) {
  for (var i = 0; i < sumArray.length; i++) {
    var total = 0;
    console.log(num);
  }
}

sumArray([1,2,3])

and when I use this code all it does is log 1 

function sumArray(num) {
  var total = 0;
  for (var i = 0; i < sumArray.length; i++) {
    console.log(total += num[i]);
  }
}

sumArray([1,2,3])

At one point I got it to return undefined three times

Upvotes: 2

Views: 72

Answers (3)

symlink
symlink

Reputation: 12209

Use Array.reduce():

function sumArray(arr) {
   return arr.reduce((acc,curr) => acc + curr);
}

console.log(sumArray([1,2,3,4]));

Upvotes: 1

kind user
kind user

Reputation: 41893

Welcome at Stack Overflow :) First of all, your naming things is kind of misleading, since sumArray argument is called num (which suggest that it accepts just a number, not an array) - I would suggest you to name it e.g. arr.

Secondly - remember about returning your total variable when the for loop finishes.

Lastly - sumArray is a function, then sumArray.length will return 1 - which is the amount of how many arguments function expects - so actually your loop will fire only once.

function sumArray(arr) {
  var total = 0;
  for (var i = 0; i < arr.length; i++) {
    total += arr[i];
  }
  
  return total;
}

console.log(sumArray([1, 2, 3]))

Upvotes: 1

Jacob
Jacob

Reputation: 78840

The problem is that you're looping over the wrong structure with this line:

for (var i = 0; i < sumArray.length; i++)

You want to loop over the num parameter you passed in. sumArray is the name of the function, and sumArray.length is the number of parameters of the function. Do this instead:

function sumArray(num) {
  var total = 0;
  for (var i = 0; i < num.length; i++) {
    console.log(total += num[i]);
  }
}

You probably want to add a return total; in there as well so that sumArray returns the sum instead of just printing the running total as it loops.

Upvotes: 2

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