Javascript binary (array) _ javascript skills

Extends the Array object and adds the binary search function to it to improve the search efficiency. In Javascript, we can use the prototype keyword to add new attributes or methods to an object. The following is a method for adding the binary search function to an Array object:

The Code is as follows:

Array. prototype. binarySearch = function (obj)
{
Var value = 0;
Var left = 0;
Var right = this. length;
While (left <= right)
{
Var center = Math. floor (left + right)/2 );
If (this [center] = obj)
{
Value = center;
}
If (obj <this [center])
{
Right = center-1;
}
Else
{
Left = center + 1;
}
}
Alert (value );
}
// The following is the test code:
Function testArrayBinarySearch ()
{
Var array = new Array ();
Var key = 678;
Var number = 1000;
For (I = 0; I <number; I ++)
{
Array. push (I );
}
Array. binarySearch (key );
}
Window. onload = function ()
{
TestArrayBinarySearch ();
}

The following is the foreign code
Javascript bipartite // Copyright 2009 Nicolas C. Zakas. All rights reserved.
// MIT-Licensed, see source file

The Code is as follows:

Function binarySearch (items, value ){
Var startIndex = 0,
StopIndex = items. length-1,
Middle = Math. floor (stopIndex + startIndex)/2 );
While (items [middle]! = Value & startIndex <stopIndex ){
// Adjust search area (adjust the search range)
If (value <items [middle]) {
StopIndex = middle-1;
} Else if (value> items [middle]) {
StartIndex = middle + 1;
}
// Recalculate middle (re-calculate the index)
Middle = Math. floor (stopIndex + startIndex)/2 );
}
// Make sure it's the right value (make sure the correct value is returned)
Return (items [middle]! = Value )? -1: middle;
}