I need to find the length of the longest string in the given array. It should return 0 if the array is empty.

So here's my try:

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;

 for(var i=0; i< arr.length; i++){
    if(arr[i] > biggestNum){
        biggestNum = arr[i];
     }
 }
}

var output = getLengthOfLongestElement(['one', 'two', 'three']);
console.log(output); // --> MUST RETURN 5

But this one did not work. Any idea or is there any better option to do this?

I need to find the length of the longest string in the given array. It should return 0 if the array is empty.

So here's my try:

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;

 for(var i=0; i< arr.length; i++){
    if(arr[i] > biggestNum){
        biggestNum = arr[i];
     }
 }
}

var output = getLengthOfLongestElement(['one', 'two', 'three']);
console.log(output); // --> MUST RETURN 5

But this one did not work. Any idea or is there any better option to do this?

• javascript
• arrays

• 5 The function doesn't return anything. – JJJ Commented Jun 20, 2017 at 7:33
• 1 Possible duplicate of Finding longest string in array – Weedoze Commented Jun 20, 2017 at 7:33

5 Answers 5

To throw another alternative into the mix: Math.max can be fed the lengths as arguments (by mapping them on the input) to get the longest string:

function getLengthOfLongestElement(arr) {
  return Math.max(0,...arr.map(s=>s.length));
}

var output = getLengthOfLongestElement(['one', 'two', 'three']);
console.log(output); 

This is apparently a reducing job and can simply be implemented as follows;

var ss = ['one', 'two', 'three'],
    ln = ss.reduce((r,s) => r > s.length ? r : s.length, 0);
console.log(ln);

You should test with arr[i].length instead of arr[i] and you should return biggestNum at the end of your function:

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;

  for (var i = 0; i < arr.length; i++) {
    if (arr[i].length > biggestNum) {
      biggestNum = arr[i].length;
    }
  }
  return biggestNum;
}

Demo:

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;

  for (var i = 0; i < arr.length; i++) {
    if (arr[i].length > biggestNum) {
      biggestNum = arr[i].length;
    }
  }
  return biggestNum;
}

var output = getLengthOfLongestElement(['one', 'two', 'three']);
console.log(output);

You should use the string length property. So instead of arr[i] it will be arr[i].length

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;

  for (var i = 0; i < arr.length; i++) {
    if (arr[i].length > biggestNum) {
      biggestNum = arr[i].length;
    }
  }

  return biggestNum;
}

For zero element just check if the array length is zero or not else arr[i].length will return the length of the string

function getLengthOfLongestElement(arr) {
  var biggestNum = 0;
  if (arr.length > 0) {
    for (var i = 0; i < arr.length; i++) {
      if (arr[i].length > biggestNum) {
        biggestNum = arr[i].length;
      }

    }
  } else if (arr.length == 0) {
    biggestNum = 0
  }
  return biggestNum

}

var output = getLengthOfLongestElement(['one', 'two', 'three']);
console.log(output);