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 insert an item into an array at a specific index (JavaScript)?
What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:
var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());
Ref: https://bit.ly/2BXbp04
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