JSFiddle - React, Tailwind, and code Playground

JavaScript

var floatView = new Float32Array( 1 );
var int32View = new Int32Array( floatView.buffer );

function toHalf( val ) {

	floatView[ 0 ] = val;
	var x = int32View[ 0 ];

	var bits = ( x >> 16 ) & 0x8000; /* Get the sign */
	var m = ( x >> 12 ) & 0x07ff; /* Keep one extra bit for rounding */
	var e = ( x >> 23 ) & 0xff; /* Using int is faster here */

	/* If zero, or denormal, or exponent underflows too much for a denormal
				 * half, return signed zero. */
	if ( e < 103 ) return bits;

	/* If NaN, return NaN. If Inf or exponent overflow, return Inf. */
	if ( e > 142 ) {

		bits |= 0x7c00;
		/* If exponent was 0xff and one mantissa bit was set, it means NaN,
							 * not Inf, so make sure we set one mantissa bit too. */
		bits |= ( ( e == 255 ) ? 0 : 1 ) && ( x & 0x007fffff );
		return bits;

	}

	/* If exponent underflows but not too much, return a denormal */
	if ( e < 113 ) {

		m |= 0x0800;
		/* Extra rounding may overflow and set mantissa to 0 and exponent
					 * to 1, which is OK. */
		bits |= ( m >> ( 114 - e ) ) + ( ( m >> ( 113 - e ) ) & 1 );
		return bits;

	}

	bits |= ( ( e - 112 ) << 10 ) | ( m >> 1 );
	/* Extra rounding. An overflow will set mantissa to 0 and increment
				 * the exponent, which is OK. */
	bits += m & 1;
	return bits;

}

console.log( toHalf( 10000 ) ); // the outout is 28898, which is 0x70E2 in hexadecimal