nextafter implemented in vanilla js without dependancies

nextafter.js

// nextafter implemented in vanilla js without dependancies
// No license, use as you wish.

function nextafter(from, to){
    if(isNaN(from) || isNaN(to))
        return NaN;    

    if(from === to)
        return to;

    if(from === 0)
        return (to > 0) ? Number.MIN_VALUE : -Number.MIN_VALUE;

    const needToIncrement = (to > from) === (from > 0);

    return incrementOrDecrementFloat(from, needToIncrement);

    function incrementOrDecrementFloat(float, increment){
        const floatFormat = new Float64Array(1);
        const uintFormat  = new Uint32Array(floatFormat.buffer);
        const maxUint32Value = 0xFFFFFFFF;

        floatFormat[0] = 1.0;
        const littleEndian = uintFormat[0] === 0x3FF00000;
        const highPart = littleEndian ? 0 : 1;
        const lowPart  = littleEndian ? 1 : 0;
    
        floatFormat[0] = float;    
    
        if(increment){
            if(uintFormat[lowPart] === maxUint32Value){
                uintFormat[highPart]++;
                uintFormat[lowPart] = 0;
            }
            else{
                uintFormat[lowPart]++;
            }
        }
        else{
            if(uintFormat[lowPart] === 0){
                uintFormat[highPart]--;
                uintFormat[lowPart] = maxUint32Value;
            }
            else{
                uintFormat[lowPart]--;
            }
        }

        return floatFormat[0];
    }
}

function testNextAfter(){
    console.assert(nextafter(Infinity,Infinity) === Infinity);
    console.assert(nextafter(Infinity,-1) === Number.MAX_VALUE);
    console.assert(nextafter(-Infinity,+1) === -Number.MAX_VALUE);
    console.assert(nextafter(-Infinity,-Infinity) === -Infinity);
    console.assert(isNaN(nextafter(NaN, 0)));
    console.assert(isNaN(nextafter(NaN, NaN)));
    console.assert(isNaN(nextafter(0, NaN)));
    console.assert(nextafter(0,1.33) === Number.MIN_VALUE);
    console.assert(nextafter(0,-989) === -Number.MIN_VALUE);
    console.assert(nextafter(-0,0) === 0);
    console.assert(nextafter(1923,1) === 1922.9999999999998);
    console.assert(nextafter(1923,1) === 1922.9999999999998);
    console.assert(nextafter(-1123123,11) === -1123122.9999999998);
    console.assert(nextafter(999.1233333,11111) === 999.1233333000001);
    console.assert(nextafter(-10, -99) === -10.000000000000002);
}

function printFloatHex(float){
    const floatFormat = new Float64Array(1);
    const uintFormat  = new Uint32Array(floatFormat.buffer);
    floatFormat[0] = float;
    console.log(uintFormat[1].toString(16).padStart(8, '0'), uintFormat[0].toString(16).padStart(8, '0'))
}