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The Math.sqrt() function returns the square root of a number, that is

x0,Math.sqrt(x)=x=the uniquey0such thaty2=x\forall x \geq 0, \mathtt{Math.sqrt(x)} = \sqrt{x} = \text{the unique} \; y \geq 0 \; \text{such that} \; y^2 = x




A number.

Return value

The square root of the given number. If the number is negative, NaN is returned.


If the value of x is negative, Math.sqrt() returns NaN.

Because sqrt() is a static method of Math, you always use it as Math.sqrt(), rather than as a method of a Math object you created (Math is not a constructor).


Using Math.sqrt()

Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095

Math.sqrt(1);  // 1
Math.sqrt(0);  // 0
Math.sqrt(-1); // NaN
Math.sqrt(-0); // -0


Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.sqrt' in that specification.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.sqrt' in that specification.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Math.sqrt' in that specification.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes1 Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes4 Yes Yes ?

See also

Document Tags and Contributors

 Last updated by: wbamberg,