Math.sqrt: How to Calculate Square Root in JavaScript

 The Math.sqrt() method returns only the positive value. The sqrt() is a static method of Math, and it can be used without creating an object.

Math.sqrt

JavaScript Math.sqrt() function is a built-in function that is used to find the square root of any number. The square roots of any number are positive and negative, respectively. The sqrt() is the static method of Math, it can be used without creating an object.

To calculate a square root of a number in Javascript, use the Math.sqrt() function. The Math sqrt() is a built-in JavaScript method 

Syntax

Math.sqrt(x)

Parameter(s)

The variable x, whose square root value is to be determined.

Return Value

The non-negative square root value.

See the following method.

Note

1. If the argument is an array with a single element, the method returns the square root of that element.
2. If the argument is an array with more than one element, the method returns NaN.
3. If the passed value is not a valid number, the method returns the NaN.
4. If a negative number is passed, a method returns NaN.
5. If an argument is a negative infinity, then this method returns NaN.
6. If an argument is a positive infinity, then this method returns positive infinity.
7. If an argument is positive zero or negative zero, this method returns the same value passed.

If the passed value is null, the method returns 0.

Compatibility(Version and above):

1. Google Chrome v1
2. Firefox v1
3. Edge v12
4. Internet Explorer v3
5. Opera v3
6. Safari v1
7. Android webview v1 
8. Chrome for Android v18
9. Firefox for Android v4
10. Opera for Android v10.1
11. Safari on iOS v1
12. Samsung Internet v1.0
13. Node.js

JavaScript version: ECMAScript 1

Consider the following examples.

Javascript Math.sqrt() example

The following example demonstrates the use of the sqrt() method.

// app.js

let a = 4;
let b = 0;
let c = 14;
let d = [9]; // array with single element

console.log(Math.sqrt(a));
console.log(Math.sqrt(b));
console.log(Math.sqrt(c));
console.log(Math.sqrt(d));

Output

node app
2
0
3.7416573867739413
3

Example 2

The following example demonstrates the cases where NaN is returned.

// app.js

let a = "Hello, world"; 		//non-numeric string
let b; 					//empty variable
let c = -4;				//negative number
let d = [1, 2, 3, 4];			//array with more than one elements
let e = {};				//empty object

console.log(Math.sqrt(a));
console.log(Math.sqrt(b));
console.log(Math.sqrt(c));

Output

node app
NaN
NaN
NaN
NaN
NaN

Example 3

The sqrt() method cannot be used with complex arguments as only integer arguments are accepted.

// Complex values cannot be passed as arguments as follows
// since only integer arguments are accepted.


console.log(Math.sqrt(2 + i));

Output

node app
/Users/krunal/Desktop/code/node-examples/es/app.js:5
console.log(Math.sqrt(2 + i));
                          ^

ReferenceError: i is not defined
    at Object.<anonymous> (/Users/krunal/Desktop/code/node-examples/es/app.js:5:27)
    at Module._compile (internal/modules/cjs/loader.js:1128:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1167:10)
    at Module.load (internal/modules/cjs/loader.js:983:32)
    at Function.Module._load (internal/modules/cjs/loader.js:891:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47

Example 4

The following example demonstrates the cases when positive infinity or negative infinity is passed as a parameter.

// app.js

var a = Number.NEGATIVE_INFINITY;
var b = Number.POSITIVE_INFINITY;

console.log(Math.sqrt(a));
console.log(Math.sqrt(b));

Output

node example4
NaN
Infinity

Example 5

The following example demonstrates the case of positive or negative zero being passed as a parameter.

// app.js

let a = 0;
let b = -0;


console.log(Math.sqrt(a));
console.log(Math.sqrt(b));

Output

node example5
0
-0

Example 6

The following example demonstrates the cases where zero is returned.

// app.js

let a = null;
let b = "";	//empty string
let c = [];	//empty array


console.log(Math.sqrt(a));
console.log(Math.sqrt(b));
console.log(Math.sqrt(c));

Output

node example6
0
0
0

A real-life example of Javascript sqrt() function

Given the two sides of a right-angled triangle, find the hypotenuse.

// Given two sides of a right-angled triangle,
// find the hypotenuse.

let side_1;
let side_2;

const r = require('readline');
const rl = r.createInterface({
  input: process.stdin,
  output: process.stdout
});

const prompt1 = () => {
  return new Promise((resolve, reject) => {
    rl.question('Side 1: ', (answer) => {
      side_1 = answer;
      resolve();
    });
  });
};

const prompt2 = () => {
  return new Promise((resolve, reject) => {
    rl.question('Side 2: ', (answer) => {
      side_2 = answer;
      resolve();
    });
  });
};

const main = async () => {
  await prompt1();
  await prompt2();
  rl.close();

  let hypotenuse = Math.sqrt(side_1 * side_1 + side_2 * side_2);
  console.log("Hypotenuse: " + hypotenuse);
}

main();

Output

Test Case 1:
->node example7
Side 1: 3
Side 2: 4
Hypotenuse: 5

Test Case 2:
->node example7
Side 1: 15
Side 2: 8
Hypotenuse: 17

See also

Javascript Math.trunc

Javascript Math.max

Javascript Math.exp

Javascript Math.pow

Javascript Math.abs