JS整形int和byte数组互相转换

 
//小端模式
function BytesToIntLittleEndian(bytes){
    var val = 0;
    for (var i = bytes.length - 1; i >= 0; i--) {        
        val += bytes[i];    
        if (i != 0) {
            val = val << 8;
        }    
    }
    return val;
}
 
//小端模式
//number 要转换的整形数值
//length 要转成什么byte数组，规定数组的长度
//如uint16，则lenght=2表示两个字节，转成的byte数组长度是length=2
//如uint32，则lenght=2表示两个字节，转成的byte数组长度是length=4
function IntToBytesLittleEndian(number, length){
    var bytes = [];
    var i = 0;
    do {
    bytes[i++] = number & (255);
    number = number>>8;
    } while ( i < length )
    return bytes;
}
 
//大端模式
function BytesToIntBigEndian(bytes){
    var val = 0;
    for (var i = 0; i < bytes.length; ++i) {        
        val += bytes[i];        
        if (i < bytes.length-1) {
            val = val << 8;
        }
    }
    return val;
}
 
//大端模式
//number 要转换的整形数值
//length 要转成什么byte数组，规定数组的长度
//如uint16，则lenght=2表示两个字节，转成的byte数组长度是length=2
//如uint32，则lenght=2表示两个字节，转成的byte数组长度是length=4
function IntToBytesBigEndian(number, length){
    var bytes = [];
    var i = length;
    do {
    bytes[--i] = number & (255);
    number = number>>8;
    } while (i)
    return bytes;
}
 
 
//测试小端模式
i = 65537
bs = IntToBytesLittleEndian(i, 4)
console.log(bs)
console.log(BytesToIntLittleEndian(bs))
 
//测试大端模式
bs = IntToBytesBigEndian(i, 2)
console.log(bs)
console.log(BytesToIntBigEndian(bs))