get maximum length of JavaScript array element

Question

If I have the following array :

array = ['a', 'abcde', 'ab'] ;

I would like to get the maximum length of the array elements ie 5 (for the element 'abcde').

I know that you can get the length of an array element via (eg) array[1].length but I don't know how to get the maximum length.

Any answer in JavaScript or jQuery would be great.

TIA

Paul Jones

Answer 1

A new answer to an old question: in ES6 you can do even shorter:

Math.max(...array.map(el => el.length));

Answer 2

One-liner for you:

 Math.max.apply(Math, $.map(array, function (el) { return el.length }));

Working example: http://jsfiddle.net/5SDBx/

You can do it without jQuery in newer browsers (or even older browsers with a compatibility implementation of Array.prototype.map) too:

Math.max.apply(Math, array.map(function (el) { return el.length }));

Answer 3

One (possibly rubbish) way of doing that, without using Jquery:

var myarray = ['a','abcde','ab'];
var maxlen = 0;
for (i=0; i<myarray.length; i++) {
  if (myarray[i].length>maxlen) {
    maxlen = myarray[i].length;
  }
}

Answer 4

You could use jQuery's each() to iterate a little nicer.

var maxLength = 0;

$.each(array, function(i, item) {
   maxLength = Math.max(maxLength, item.length);
});

Or plain ol' JavaScript...

var maxLength = 0;

for (var i = 0, length = array.length; i < length; i++) {
   maxLength = Math.max(maxLength, array[i].length);
};

Answer 5

By using Array.prototype.reduce(), you can elegantly perform a Math.max() calculation for each item in the array. It does not matter whether the items in the array are string or sub-arrays (2D array, matrix, etc.), this will work because String and Array both have a prototype.length() function.

I also added a check for integer values per your comment above.

function arrayItemMax(arr) {
    return arr.reduce(function (result, val) {
        return Math.max(result, !isNaN(val) ? parseInt(val) : val.length);
    }, 0);
}

function print(text) {
  document.getElementsByTagName('body')[0].innerHTML += text + '<br />';
}

print(arrayItemMax(['a', 'abcde', 'ab'])); // 5
print(arrayItemMax([1, 5, 2]));            // 5
print(arrayItemMax(['1', '5', '2']));      // 5

One liner:

function(a){return a.reduce(function(r,v){return Math.max(r,!isNaN(v)?parseInt(v):v.length);},0);}

Answer 6

In such cases, there is a very useful function. Array.reduce

['a', 'abcde', 'ab'].reduce((r,s) => r.length > s.length ? r : s, 0);