How to Search in Javascript | Binary Search Algorithm Implementation in Javascript

How to implement binary search algorithm in JavaScript? What is binary search in programming? What is binary search algorithm? Binary search is an algorithm for finding an element within a sorted array. It works repeatedly dividing the search interval in half, and checking whether the target value is in the lower or upper half.

The basic idea behind the binary search algorithm is to start with the middle element of the array and compare it to the target value. If the middle element is the target value, the search is complete.

If the target value is less than the middle element, the algorithm looks in the left half of the array. If the target value is greater than the middle element, the algorithm looks in the right half of the array. This process is repeated until the target value is found or the array is completely searched.

Binary search is much more efficient than other algorithms like linear search when searching large arrays. It is commonly used in applications such as databases, search engines, and sorting algorithms.

It's important to note that for binary search to work correctly the input array must be sorted. So how to implement binary search in JavaScript?

Define a binary search function in JavaScript, to search for a target value within a given array. It takes in two arguments, the array to be searched (arr) and the target value (target). Initialize two variables, left and right, to represent the start and end of the portion of the array that is being searched. set left to 0, which is the first index of the array. Set right the last index of the array by subtracting 1 from the length of the array.

Start a while loop which continues to run as long as left is less than or equal to right. This is necessary because if left becomes greater than right,
it means that the target value is not present in the array. Inside the while loop, calculate the middle index of the current search range by dividing the sum of left and right by 2 and rounding down using the Math floor function. Store this middle index in a variable called 'mid'.

Check if the value at the middle index of the array (arr[mid]) is equal to the target value (target). If it is, return the middle index as the result of the search. If the value at the middle index is not equal to the target value, check if it is less than the target value. If it is, narrow the search range by setting left to one greater than the middle index. This is because all the values to the left of the middle index are less than the target value, so they can be ignored in future searches.

Otherwise, if the value at the middle index is greater than the target value, narrow the search range by setting right to one less than the middle index. This is because all the values to the right of the middle index are greater than the target value, so they can also be ignored.

Once the while loop finishes and if the target value is not found, return -1 to indicate that the target value is not present in the array. Call the function with array and the element (in our case the number), that will return index of that number in the array if its present.

Basically, This function takes in an array and a target value as its inputs, and returns the index of the target value in the array if it is present, or -1 if it is not present. The function uses a while loop to repeatedly divide the portion of the array being searched in half until the target value is found or the search range becomes empty.

Also

- It's important to note that the input array must be sorted in ascending order for the binary search algorithm to work correctly.
- It's also worth mentioning that there is an improved version of the binary search called "interpolation search", which is used when the values in the array are uniformly distributed, this algorithm uses the value of the target to estimate the position of it instead of the middle.

But anyways, this is how we can implement binary search algorithm in JavaScript.

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