To find the Power of a number in JavaScript you can use the readily available function Math.pow().
But sometimes, especially in the interviews they might ask you to write a simple JavaScript program to calculate the power of a number without using the JavaScript pow() function.
Here is a small example of “Power of a number”
52 = 5 * 5, value is 25
Here in the above expression example, 5 is the base & 2 is the exponent
Another example, 53 = 5 * 5 * 5, value is 125
So basically we need get two values from the user, base & exponent then to find the power, just loop exponent times and multiple the base value.
Let’s write a custom JavaScript function to find the power of a number:
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function PowerOfNumber(b,e){ var i, pow = 1; //loop exponent times for(i=0; i<e; i++){ //multiple the base value pow = pow*b; } return pow; } |
b and e is the base and exponent in the above function
Let’s write a HTML example to see the output:
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<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title>Javascript to find power of a number</title> <meta name="viewport" content="width=device-width, initial-scale=1"> <!-- Load Bootstrap library for better UI look & feel --> <link rel="stylesheet" type="text/css" media="screen" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" /> <script> function calcPower() { //get the value of base & power var b = document.getElementById("pow").value; var e = document.getElementById("exp").value; var res; res = PowerOfNumber(b,e); document.getElementById("res").innerHTML = res; } function PowerOfNumber(b,e){ var i, pow = 1; //loop exponent times for(i=0; i<e; i++){ //multiple the base value pow = pow*b; } return pow; } </script> </head> <body> <div class="container"> <br /> <h2>Javascript to find Power of a number without using pow()</h2> <br /> <div class="row"> <div class="col-lg-4"> <div class="input-group mb-4"> <input type="number" class="form-control" id="pow" placeholder="Base" min="1"> <div class="input-group-prepend"> <span class="input-group-text">-</span> </div> <input type="number" class="form-control" id="exp" placeholder="Exponent" min="1"> <button type="submit" class="btn btn-primary" onclick="calcPower()">Submit</button> </div> <div>Result: <span id="res"></span> <div> </div> </div> </div> </div> </body> </html> |
See the demo of this above script here:
