YourJS candidate function: fround()

fround.js

// Not available in IE.
// 
var fround;
(function (array) {
  fround = function(x) {
    return array[0] = x, array[0];
  };
})(new Float32Array(1));

//\\
// Examples from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/fround
fround(1.5); // -> 1.5
//\\
fround(1.5) === 1.5; // -> true

//\\
fround(1.337); // -> 1.3370000123977661
//\\
fround(1.337) === 1.337; // -> false

//\\
2 ** 150; // -> 1.42724769270596e+45
//\\
fround(2 ** 150); // -> Infinity

//\\
fround('abc'); // -> NaN
//\\
fround(NaN); // -> NaN

https://www.yourjs.com/console/?gist=b2cf4654d579575da6c929622edfc499&file=fround.js