JavaScript Sort String Arrays

Order the elements in a string array with the sort method. The array is modified in-place.

Sort. Imagine a million lines of text. With no sorting it is impossible to find a certain line. But with sorting it can be easily located.

In JavaScript we discover a sort method on arrays. This method can receive a function that determines how elements are sorted. With no arguments, it sorts in an ascending order.Array

First example. Here we introduce an array called "patterns" that has 3 strings in it. We then invoke sort() on our patterns array.

Result: The array's elements are reordered. The string "abc" comes first as it is the earliest alphabetically.

JavaScript program that uses sort, string array var patterns = ["def", "xyz", "abc"]; // Sort the string array. patterns.sort(); console.log("SORTED: " + patterns); Output SORTED: abc,def,xyz

Modifies in-place. We can assign a variable to the result of sort() but there is no point to this. Sort() modifies the existing array.

Tip: To keep the originally-ordered array around, a copy of the array would need to be made.

JavaScript program that shows sort modifies array var patterns = ["def", "xyz", "abc"]; var result = patterns.sort(); // The original array is sorted. console.log("VARIABLE 1: " + patterns); console.log("VARIABLE 2: " + result); Output VARIABLE 1: abc,def,xyz VARIABLE 2: abc,def,xyz

Integer array. In most programming languages numbers are sorted as numbers. But in JavaScript we find that numbers are sorted as strings. So 10 comes before 2 because 1 comes before 2.

Here: We override the default sorting behavior with a function. In our function "compare" we sort two integers by their difference.

So: Numbers are sorted by their numeric values, and smaller numbers precede larger ones.

JavaScript program that uses sort, integer array var numbers = [-1, 100, 10, 1, 2, 3]; // Numbers are sorted as strings by default. numbers.sort(); console.log("SORT 1: " + numbers); // This function sorts numbers. // ... We compare two numbers by subtracting one from the other. var compare = function(a, b) { return a - b; }; // Sort numbers in a numeric way. numbers.sort(compare); console.log("SORT 2: " + numbers); Output SORT 1: -1,1,10,100,2,3 SORT 2: -1,1,2,3,10,100

LocaleCompare. The localeCompare method handles non-ASCII characters (like those with accents) in a correct way. It should be used when sorting strings.

Here: We use localCompare to sort a string array from low to high (in ascending alphabetical order).

Then: We use a descending string sort. We compare the second string to the first in reverseAlphabetical.

Tip: It is possible to call reverse() after sorting a string array. But with localeCompare we can directly sort in reverse order.

JavaScript program that uses localeCompare var unsorted = ["def", "xyz", "ghi", "abc"]; function alphabetical(a, b) { // Use localeCompare. return a.localeCompare(b); } function reverseAlphabetical(a, b) { // Use localeCompare with second compared to first. return b.localeCompare(a); } // Sort in alphabetical order. unsorted.sort(alphabetical); console.log("LOCALECOMPARE 1: " + unsorted); // Sort in reverse alphabetical order. unsorted.sort(reverseAlphabetical); console.log("LOCALECOMPARE 2: " + unsorted); Output LOCALECOMPARE 1: abc,def,ghi,xyz LOCALECOMPARE 2: xyz,ghi,def,abc

Some notes. Arrays are common in JavaScript programs. We use them everywhere. With sort() we change the ordering of elements in arrays to conform to a pattern.

The Dev Codes

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

TheDeveloperBlog.com

JavaScript Sort String Arrays

Related Links:

.Net

Java

Related Links