The use, parameters, and sorting principles of the sort () method in JS

The sort () method is used to sort elements of an array. Syntax: Arrayobject.sort (sortby), parameter SortBy Optional. Specifies the sort order. Must be a function. Note: If the method is called without parameters , the elements in the array are sorted alphabetically, more precisely, by the order in which the characters are encoded . To do this, you should first convert the elements of the array to a string, if necessary, for comparison.

If you want to sort by other criteria, you need to provide a comparison function that compares two values and returns a number that describes the relative order of the two values. The comparison function should have two parameters A and B with the following return values:

If a is less than B, a value that is less than 0 is returned if a should appear before B in the sorted array.

If a equals B, 0 is returned.

If a is greater than B, a value greater than 0 is returned. As Example 3.

Example 1: We will create an array and sort alphabetically:

<ScriptType="Text/javascript" >

var arr = new array (6)
Arr[0] = "George"
Arr[1] = "John"
Arr [2] = "Thomas"
Arr[3] = "James"
Arr[4] = "adrew"
Arr[5] = "Martin"

document.write ( arr + "<br/>")
document.write (Arr.sort ())

</SCRIPT>

Output:

George,John,Thomas,James,Adrew,MartinAdrew,George,James,John,Martin,Thomas

Example 2: We will create an array and sort alphabetically:

<Scripttype= "Text/javascript" >var arr = new array (6) arr[0] = " ten "Arr[1] =  "5" Arr[2] =  "Max" Arr[3] = " Arr[4] =  "1000 "Arr[5] = " 1 "document.write (arr +  "<br/>") document.write (Arr.sort ()) </ Script>                

Output:

10,5,40,25,1000,11,10,1000,25,40,5

例3：

Note that the above code does not sort numbers by numeric values, and to do this, you must use a sort function:

<ScriptType="Text/javascript" >functionSortnumber(A, B) {return  -A-B  } var arr = new Array (6) arr[0] = " ten "Arr[1] =  "5" Arr[2] =  "Max" Arr[3] = " Arr[4] =  "1000 "Arr[5] = " 1 "document.write (arr +  "<br/>") document.write (Arr.sort (sortnumber)) </ SCRIPT>             

Output:

10,5,40,25,1000,11,5,10,25,40,1000


Example 4: Sorting numbers from large to small


Numarr.sort (function compare (A, b) {return b-a



</script>

Results:
34 23 23 12 5 4 2 1

My understanding is that if the result of the comparison function returns a positive value, the second argument is queued forward, returning a negative value, and the second parameter is temporarily ranked after the first argument.

Reference from:

1190000000410506

Http://www.jb51.net/article/4168.htm

The use of the sort () method in JS, parameters, and sorting principles