Let's talk in depth about the usage skills of Array's sort method. Detailed review of the sortBy method in prototype.js_javascript skills

The Array.prototype.sort method is to sort the array. This method takes a function parameter to specify the sorting rule.

Let’s first look at the simple application of sort:


var arr=[2,1,3,4];
alert(arr.sort()) // [1,2,3,4] Arrange from small to large

//Now by Arrange from big to small to get [4,3,2,1]
alert(arr.sort(function(left,right){return left>right?-1:1}))

// Here, the sort method uses the return value of the parameter function 1 or -1 to decide whether to sort in order or inverted

Remember what I told you before about using the Function.apply method to get the largest element in the array Method?
The article uses two different methods to get the maximum value in the array.
Now sort can also show it off.

var arr=[2,1,3, 4];
var minValue=arr.sort()[0];
var maxValue=arr.sort()[arr.length-1] // arr.sort().pop()

How about this? This is also an alternative implementation method. There is no need to write a loop traversal.
However, I must point out that this method is the least efficient. For dozens or hundreds of elements For arrays, you can still use this technique.
However, if the array is very large, using the sort() method can be so slow that it makes you want to smoke

Further discuss how sort sorts complex data structures.
1. Sorting multi-dimensional arrays


var arr=[
                                                                                                                                   >                                                                                                                                                                      ("n"))
alert("Now sort by the third column " arr.sort(function(left,right){return left[2]>right[2]?1:-1}).join("n"))
alert("Now sort by the third column upside down n" arr.sort(function(left,right){return left[2]>right[2]?-1:1}).join("n"))
2. Sorting of complex data structures

Array.prototype.each=function(f){for(var i=0;ifunction showName(item ){alert(item.name)}; //Print name

var arr=[
                                                  ;
arr.sort(function(left,right){return left.money>right.money?-1:1}).each(showName)
3. Sorting tables, this topic I I talked to you yesterday.
See:
http://www.cnblogs.com/ashun/archive/2006/11/30/appendChild_table_sort.html

More complex table sorting ( Also uses Array’s sort function):
http://community.csdn.net/expert/Topicview2.asp?id=5174915


4. There is an idea for sort in Protype.js A very clever extension, let’s look at his code first

1 sortBy: function(iterator) {
2 return this.collect(function(value, index) {
3 return {value: value, criteria: iterator(value, index)};
4 }).sort(function(left, right) {
5 var a = left.criteria, b = right.criteria;
6 return a
b ? 1 : 0;
7 }).pluck('value');
8 },


This sortBy allows passing in a function and sorting each element of the array. An element is used as a parameter to execute the function, and finally the results returned by the function are sorted.
Let me break down this function below.
The collect method is actually the map method. It is equivalent to
Array.prototype.map=function (f){ for(var i=0;ret=[];i return ret
}

For example, now
arr=[2,1,4,3]
iterator=function(x){return x*x}

1-3 lines of code will get such an array
[
{value:2,criteria:4},
{value:1,criteria:1},
{value:4,criteria:16},
{value:3,criteria:9}
]

4-6 lines of code will sort the array according to criteria:, from small to large .After sorting, we get
[
{value:1,criteria:1},
{value:2,criteria:4},
{value:3,criteria:9},
{value:4,criteria:16}
]

The 7th line of code is the simplest. It takes the value attribute of each element and finally gets [1,2,3,4] to implement arr sortBy(function...) sorting


Maybe my language expression ability is limited. When I talk about sortBy of prototype.js, I just don’t know how to express it in words.
It makes everyone so I’m really sorry for taking the trouble to read the explanation code I wrote!