JavaScript: Search JavaScript arrays with a binary search
JavaScript Function: Exercise-18 with Solution
Write a function for searching JavaScript arrays with a binary search.
Note : A binary search searches by splitting an array into smaller and smaller chunks until it finds the desired value.
Pictorial Presentation:

Sample Solution: -
HTML Code:
<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Search JavaScript arrays with a binary search</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function array_binarySearch(narray, delement) {
var mposition = Math.floor(narray.length / 2);
if (narray[mposition] === delement){
return mposition;
}
else if (narray.length === 1)
{
return null;
}
else if (narray[mposition] < delement) {
var arr = narray.slice(mposition + 1);
var res = array_binarySearch(arr, delement);
if (res === null)
{
return null;
}
else {
return mposition + 1 + res;
}
}
else {
var arr1 = narray.slice(0, mposition);
return array_binarySearch(arr1, delement);
}
}
var myArray = [1, 2, 3, 5, 6, 7, 10, 11, 14, 15, 17, 19, 20, 22, 23];
console.log(array_binarySearch(myArray, 6));
Sample Output:
4
Flowchart:

Live Demo:
See the Pen JavaScript - Search JavaScript arrays with a binary search-function-ex- 18 by w3resource (@w3resource) on CodePen.
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Next: Write a JavaScript function that returns array elements larger than a number.
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JavaScript: Tips of the Day
How to check whether a string contains a substring in JavaScript?
ECMAScript 6 introduced String.prototype.includes:
const string = "foo"; const substring = "oo"; console.log(string.includes(substring));
includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found:
var string = "foo"; var substring = "oo"; console.log(string.indexOf(substring) !== -1);
Ref: https://bit.ly/3fFFgZv
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