Find The Largest Number

Table of Contents

In this example, we will receive a two-dimensional array of numbers as input and the JavaScript function will find the largest in each sub-array and return the result in a new array.

The program takes following steps to compute the results:

Receive an array with many sub-arrays.
Set a maximum number variable.
Loop through each sub-array,compare it with maximum and if the array number greater than maximum then get that array number as new maximum.
Push the new maximum from the sub-array into a new result array.
Repeat the above two steps for all sub-arrays.
Display the resultant new array which contains maximum from all sub-arrays.

For example,

Suppose our array is following

[[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], [-72, -3, -17, -10]]

Each of the sub-array has maximum and we will collect them in a new array. The result is as follows.

[25, 48, 21, -3]

Program Code: Find the Largest Number

<!DOCTYPE html>
<html>
<head>
   <title>Find Largest number from Array</title>
   <meta charset="utf-8">
   <style>
   main{
    width:40%;
	padding:2%;
	margin:10% auto;
	background:DodgerBlue;
	text-align:center;
   }
     #in{
	 
	  padding:10px;
	  width:150px;
	  background:whitesmoke;  
	  margin:auto;
	 }
	 
	 button{
	 padding:10px;
	 margin:10px;
	 
	 }
   </style>
</head>
<body>
  <main>
     <h1 id="out">Output here</h1>
     <p>[[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], 
     [-72, -3, -17, -10]]</p>
     <button onclick="largestNumber()">Find Largest Number</button>
     <button onclick="MyClear()">Clear</button>
  </main>
  <script>
     function largestNumber() {
       // You can do this!
       var arr = [[17, 23, 25, 12], [25, 7, 34, 48], 
       [4, -10, 18, 21], [-72, -3, -17, -10]];
       var maxNumber = -20;
       var result = [];
       for(let i = 0;i< arr.length;i++){
         for(let j = 0; j < arr[i].length;j++){
      
            if (arr[i][j] > maxNumber){
                maxNumber = arr[i][j];
              }
          }
        result.push(maxNumber);
        maxNumber = -20;
        }
        document.getElementById("out").innerHTML = result;
      }
  </script>
</body>
</html>

Note that we did not receive input from a HTML control, but directly assigned it to a variable. The output is display in the browser though.

Output To Browser: Find the Largest Number