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This is an experimental technology, part of the Harmony (ECMAScript 6) proposal.
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.


The Math.fround() function returns the nearest single precision float representation of a number.




A number.


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


Math.fround(0)     // 0
Math.fround(1)     // 1
Math.fround(1.337) // 1.3370000123977661
Math.fround(1.5)   // 1.5
Math.fround(NaN)   // NaN


This can be emulated with the following function, if Float32Array are supported:

function fround(x) {
  var f32 = new Float32Array(1);
  return f32[0] = x, f32[0];


Specification Status Comment
ECMAScript Language Specification 6th Edition (ECMA-262) Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

  • The Math object it belongs to.

Document Tags and Contributors

Last updated by: fscholz,