直接上代码，仔细看

function stringToUtf8Array0(str) {
	  var utf8 = [], c = 0, c1 = 0;
	  for(var i = 0; i < str.length; i++) {
	    c = str.charCodeAt(i);
	    if(c < 0x80) {
	      utf8.push(c)
	    } else if(c < 0x800) {
	      utf8.push(0xc0 | (c >> 6), 0x80 | (c & 0x3f))
	    } else if(c < 0xd800 || c >= 0xe000) {
	      utf8.push(0xe0 | (c >> 12), 0x80 | ((c>>6) & 0x3f), 0x80 | (c & 0x3f))
	    } else {
	      i++;
	      c1 = str.charCodeAt(i);
	      c = 0x10000 + (((c & 0x3ff)<<10) | (c1 & 0x3ff));
	      utf8.push(0xf0 | (c >>18), 0x80 | ((c>>12) & 0x3f), 0x80 | ((c>>6) & 0x3f), 0x80 | (c & 0x3f))
	    }
	  }
	  return utf8
	}
	
function stringToUtf8Array1(str) {
	var buf = encodeURI(str), len = buf.length, utf8 = [], c = 0;
	for(var i = 0; i < len; i++) {
		c = buf.charCodeAt(i);
		if(c == 37) {
			c = parseInt(buf.substr(i + 1, 2), 16);
			i+=2
		} else {
			c = buf.charCodeAt(i)
		}
		utf8.push(c)
	}
	return utf8
}

function stringToUtf8Array2(str) {
	var utf8 = [], i = 0, buf = unescape(encodeURIComponent(str)), len = buf.length;
	for(; i < len; i++) {
		utf8.push(buf.charCodeAt(i))
	}
	return utf8
}

function stringToUtf8Array3(str) {
	var enbytes = new TextEncoder().encode(str), len = enbytes.length, utf8 = [], i = 0; 
	for(; i < len; i++) {
		utf8.push(enbytes[i])
	}
	return utf8
}

function toHexStr(utf8arr) {
  var hexstr = '', mod = 0, block = 32;
  for(var i = 0; i < utf8arr.length; i++) {
    mod = i % block;
    if(i > 0) {
      if(mod == 0) {
        hexstr += '\n'
      } else {
        hexstr += ' '
      }
    }
    hexstr += utf8arr[i].toString(16)
  }
  return hexstr
}