A summary of various methods of JavaScript array ordering

Order of singular groups

Sort () function

The sort method of an array object can rearrange the array elements in a certain order. Usually, they are arranged in the order of subtitles. When sort () is used, the comparison function is executed each time the two elements are compared, and two elements are passed as arguments to the comparison function. The comparison function has the following two return values.

1, if the return value is greater than 0, swap the position of two elements
2. If the return value is less than or equal to 0, the operation is not performed.

JavaScript code

Example 1

The following array is assumed:

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var homes = [{ "h_id": "3", "City": "Dallas", "State": "TX", "Zip": "75201", "Price": "162500" }, { "h_id": "4", "City": "Bevery Hills", ' State ': ' CA ', "Zip": "90210", "Price": "319250" }, { "h_id": "5", "City": "New York", "State": "NY", "Zip": "00010", "Price": "962500" }];

You can sort the arrays by price by the following methods:

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Homes.sort (function (a,b) {return parsefloat (A.price)-parsefloat (B.price)});

Ordering of elements in a single array

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<script type= "Text/javascript" > function Sort_desc (str)//descending array of functions { Str.sort (function compare (a,b) {return b-a;}); /is the descending of the K element in the object of 1 in the array return str; } function Sort_asc (str)//Array Ascending { Str.sort (function compare (a,b) {return a-b;}); /refers to the ascending of the K element in an object of 1 in the array return str; } var tt=[4,10,8,98,2]; var bb=[]; Bb=sort_desc (TT); document.write (bb+ "* * Descending output"); var cc=[89,2,100,5]; var dd=[]; DD=SORT_ASC (CC); document.write ("document.write (dd+ "* * Ascending output"); </script>

the sort of two-dimensional array.

1, sorted by numerical value

Suppose you have the following array

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var arr = [[1, 2, 3], [7, 2, 3], [3, 2, 3]];

Here, if we're going to sort by the first column of each sub array, we can define a comparison function:

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Arr.sort (function (x, y) { return x[0]–y[0]; });

What is the function of the comparison function here? The array, in turn, copies the elements of the array to x,y, for example, first assign arr[0] to x,arr[1] and then use x[0]–y[0], depending on the value returned, if it returns a number greater than 0, then the x in the array is placed behind the Y, and if 0 is returned, Less than 0 puts X in front of y, then the first one is sorted after the following two, until the entire array sort completes. This is the default ascending comparison function, and if you want to sort in descending order, simply change the comparison and change to return y[0]–x[0], where we x[0 the order by the first column, where we can sort by other columns. The sorting here defaults to modifying the ARR array structure, so sorting the arr is an array in ascending order of the first column.

2, sorted by string

Sorted by string, we can use the Localecompare method provided by JS,
Localecompare function: Compares two strings in a local-specific order.
The use rule for the Localecompare method is Stringobject.localecompare (target), and if Stringobject is less than target, Localecompare () returns a number less than 0. If the stringobject is greater than target, the method returns a number greater than 0. If two strings are equal, or if there is no difference based on local collations, the method returns 0, and the comparison uses local rules, which mean that the local rules are sorted by using the underlying rules of the operating system to sort the local characters. The comparison, by default, such as the greater-than number, is simply a comparison of the number of two-character Unicode, which is inconsistent with many languages.
Like what

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var arr = [['], ' country '], [' Ah ', ' '], [' Oh ', ']]; Arr.sort (function (x, y) { Return X[0].localecompare (y[0]); });

The result is sorted by the phonetic alphabet of the text in the first column, if you have English, the default is to put English in front, if it is pure English, will be alphabetical, uppercase in the lower case, so you can achieve the sort of string, including Chinese and English mixed row. As to the descending order, the method is the same as above, changed to return Y[0].localecompare (X[0]); Can.

Array go heavy, sort, look for index

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Array to weight Array.prototype.distinct = function () { var filtered= []; var _a = {}; for (var i = 0;i<this. length;i++) { if (!_a[this[i]]) {//if already available, no longer added _a[this[i]] = 1; Filtered.push (This[i]) } } return filtered; }; Finding indexes by the method of binary Division function Search (arr,item,lower,upper) { Lower = Lower | | 0; Upper = Upper | | Arr.length-1; if (lower = = Upper) { if (item = = Arr[upper]) { return upper; }else{ return-1; } }else{ var middle = parseint ((lower+upper)/2); if (item > A[middle]) { Return search (Arr,item,middle+1,upper); }else{ Return search (Arr,item,lower,middle); } } } var a = [10,15,3,4,5,6,7,8,9,3,8,9]; A = A.distinct (); [10, 15, 3, 4, 5, 6, 7, 8, 9] A.sort (function (a,b) {return a-b;}); Sort [3, 4, 5, 6, 7, 8, 9, 10, 15] Alert (Search (a,9)); 6

Face questions encountered

Given An array of may contain nested arrays, return a flattened array. Input and out put are illustrated as follows.

Sorts output that contains nested arrays. The * part is the code that needs to be written out.

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var input = [{A: ' A '}, ' B ', [' C ', ' d '], [' E ', [' F ']], ' G ']; function Flatten_array (arr) { var out = []; *******; return out; }

This topic is clearly supposed to be solved by recursion: (Revise thanks @felix021 remind ...)

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var input = [ {A: ' A '}, ' B ', [' C ', ' d '], [' E ', [' F ']], ' G ']; var out = []; Loop (input); Function Loop (object) {   for (var an in object) {     if (typeof (object) = = ' object ') { br>       Loop (Object[a]);    }else{       out.push (Object[a]);    } & nbsp } Console.log (out);