如何按字符串值对数组中的对象数组进行排序？

Question

I have an array of objects.

In each object, I'm targeting a property called "myLevel". The values for this property vary in the following string syntax:

 [
 {myLevel : 'CAT I #4'},
 {myLevel : 'CAT I #6'},
 {myLevel : 'CAT I #2'},
 {myLevel : 'CAT II #15'},
 {myLevel : 'CAT III #1'},
 {myLevel : 'CAT II #7'},

   ]

How can I sort the array so that the objects are rearranged in ascending order like so:

[
 {myLevel : 'CAT I #2'},
 {myLevel : 'CAT I #4'},
 {myLevel : 'CAT I #6'},
 {myLevel : 'CAT II #7'},
 {myLevel : 'CAT II #15'},
 {myLevel : 'CAT III #1'}
   ] 

Answer 1

Use Array.sort, and in the passed function, split the strings by the # sign, compare the first half as string, if even, compare second half as int with call parseInt.
In reality, this will be slow if there are a lot of records. You should really store the records as an object with 2 integers for cat and level. Thia will make sorting more efficient. You can override the toString function to display it the way you like.

Answer 2

Use RegEx to match the parts, then check those parts individually

var arr = [
 {myLevel : "CAT I #4"},
 {myLevel : "CAT I #6"},
 {myLevel : "CAT I #2"},
 {myLevel : "CAT II #15"},
 {myLevel : "CAT III #1"},
 {myLevel : "CAT II #7"}
];

var sorted = arr.sort(function(a,b){
 var left = a.myLevel.match(/CAT (I+) #([0-9]+)/);
 var right = b.myLevel.match(/CAT (I+) #([0-9]+)/);
 if(left[1].length==right[1].length){
  return left[2]-right[2];
 }else return left[1].length-right[1].length;
});

The match returns

[0] whole matched string
[1] all the `I`'s
[2] the number after the #

The first if is to check if the I count is the same, if it is we need to check by the number.

If we need to check by the number, we just need to return the difference between them.

If we don't need to check by the number we just need to return the difference between the amount of I 's

Answer 3

Use sort with a comparator.

// assume we want to have arbitrary roman numerals - we should have some form of lookup
var numeralLookup = {
  I: 1,
  II: 2,
  III: 3,
  IV: 4
} //etc

// helper function - parse Roman Numeral from your string
function getNumeral(str) {
  return str.split()[1]
}

// helper function - parse number after '#' from your string
function getNumber(str) {
  return parseInt(str.slice(str.indexOf('#') + 1))
}

// sort
arr.sort(function(a, b) {
  var aNum = numeralLookup[getNumeral(a.myLevel)];
  var bNum = numeralLookup[getNumeral(b.myLevel)];

  return aNum === bNum ? getNumber(a.myLevel) - getNumber(b.myLevel) : aNum - bNum;
})

Answer 4

Believe it or not a faster alternative to Array.sort is Underscore's sortBy function. Check out their documentation here . The library has all sorts of great utilities for doing stuff like this.

var stooges = [{name: 'moe', age: 40}, {name: 'larry', age: 50}, {name: 'curly', age: 60}];
_.sortBy(stooges, 'name');
=> [{name: 'curly', age: 60}, {name: 'larry', age: 50}, {name: 'moe', age: 40}];