16进制的字符串 转换为整数
function string_hex2int(hex) {
var len = hex.length, a = new Array(len), code;
for (var i = 0; i < len; i++) {
code = hex.charCodeAt(i);
if (48<=code && code < 58) {
code -= 48;
} else {
code = (code & 0xdf) - 65 + 10;
}
a[i] = code;
}
return a.reduce(function(acc, c) {
acc = 16 * acc + c;
return acc;
}, 0);
}
// 15 + 16 * 13 + 256 = 479
console.log(string_hex2int("1df"));