从字符串数组中获取最大值/最小值（javascript）

Question

Any ideas to calculate min / max from array of strings?

var arr = ['aab','aac','aad','abx'];

So far i have considered to use .sort() function depending max / min, and get first element of result.

But maybe you know better preforming solution?

EDIT: Array size is below 1k elements. By Min /max i meant alphabetic sort: first and last element.

Answer 1

Iterate through your list and update min and max in each iteration step

 function getMinMax(arr) { if (!arr) { return null; } var minV = arr[0]; var maxV = arr[0]; for (a of arr) { if (a < minV) minV = a; if (a > maxV) maxV = a; } return [minV, maxV]; } console.log(getMinMax(['abc', 'aaa', 'abb']));

It should be much faster than sort() for large arrays. This algorithm is O(n) while sort() is at least O(n log(n)).

Answer 2

Here are a few solutions to wrap your head around:

Min/max based on length

const output = arr.sort((a, b) => a.length - b.length);

Min/max as in alphabetical order

const output = arr.sort();

Extract the minimum and max

const max = arr.sort(() => 1)[0];

Answer 3

If you don't want to use a sort,.

Another option is to use Array.reduce to maintain the min & max values.

Below is a working snippet showing this.

ps. Your test data already had the min as the first element, and max as the last element, so I've altered the example array to have zzz , that of course would be max .

 var arr = ['aab','aac','zzz','aad','abx']; var ret = arr.reduce((a, v) => { a.min = a.min === null ? v : v.localeCompare(a.min) < 0 ? v : a.min; a.max = a.max === null ? v : v.localeCompare(a.max) > 0 ? v : a.max; return a; }, {min: null, max: null}); console.log(ret);

Answer 4

To extend @Keith's answers.. if we want min or max only then reduce will be 1-liner.

var arr = ['aab','aac','aad','abx']
var min = arr.reduce((min,c) => c < min? c : min) // 'aab'
var max = arr.reduce((max,c) => c > max? c : max) // 'abx'

Answer 5

You can use reduce in one pass but have to check what to return if the array is empty (currently returns undefined for both min and max)

 const arr = [ 'aab', 'aac', 'aad', 'abx', ]; console.log( arr.reduce( ([min, max], item) => [ min.localeCompare(item) > 0 ? item : min, max.localeCompare(item) < 0 ? item : max, ], [arr[0], arr[0]], ), );

Answer 6

This is what I did (note that it mutates the original array):

 const myArray = ['beta', 'alpha', 'zeta', 'delta']; const min = myArray.sort()[0]; const max = myArray.reverse()[0]; console.log({ min, max });