EN
JavaScript - convert string to bytes array (UTF-8)
6 points
In this short article, we would like to show, how using JavaScript, convert string to UTF-8 bytes array.
This solution works under older web borsers and Node.js.
xxxxxxxxxx1
const toBytes = (text) => {2
const surrogate = encodeURIComponent(text);3
const result = [];4
for (let i = 0; i < surrogate.length;) {5
const character = surrogate[i];6
i += 1;7
if (character === '%') {8
const hex = surrogate.substring(i, i += 2);9
if (hex) {10
result.push(parseInt(hex, 16));11
}12
} else {13
result.push(character.charCodeAt(0));14
}15
}16
return result;17
};18
19
20
// Usage example:21
22
const bytes = toBytes('Some text here...'); // converts string to UTF-8 bytes23
24
console.log(bytes); // [83, 111, 109, 101, 32, 116, 101, 120, 116, 32, 104, 101, 114, 101, 46, 46, 46]
This solution appeard in the major web browsers around 2014-2020 and in Node.js v11.
xxxxxxxxxx1
const encoder = new TextEncoder('UTF-8');2
3
const toBytes = (text) => {4
return encoder.encode(text);5
};6
7
8
// Usage example:9
10
const bytes = toBytes('Some text here...'); // converts string to UTF-8 bytes11
12
console.log(bytes); // [83, 111, 109, 101, 32, 116, 101, 120, 116, 32, 104, 101, 114, 101, 46, 46, 46]
This solution has quite good performance, it works in older web browsers and Node.js.
xxxxxxxxxx1
const toBytes = (text) => {2
const result = [];3
for (let i = 0; i < text.length; i += 1) {4
const hi = text.charCodeAt(i);5
if (hi < 0x0080) {6
// code point range: U+0000 - U+007F7
// bytes: 0xxxxxxx8
result.push(hi);9
continue;10
}11
if (hi < 0x0800) {12
// code point range: U+0080 - U+07FF13
// bytes: 110xxxxx 10xxxxxx14
result.push(0xC0 | hi >> 6,15
0x80 | hi & 0x3F);16
continue;17
}18
if (hi < 0xD800 || hi >= 0xE000 ) {19
// code point range: U+0800 - U+FFFF20
// bytes: 1110xxxx 10xxxxxx 10xxxxxx 21
result.push(0xE0 | hi >> 12,22
0x80 | hi >> 6 & 0x3F,23
0x80 | hi & 0x3F);24
continue;25
}26
i += 1;27
if (i < text.length) {28
// surrogate pair29
const lo = text.charCodeAt(i);30
const code = 0x00010000 + (hi & 0x03FF) << 10 | lo & 0x03FF;31
// code point range: U+10000 - U+10FFFF32
// bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx33
result.push(0xF0 | code >> 18,34
0x80 | code >> 12 & 0x3F,35
0x80 | code >> 6 & 0x3F,36
0x80 | code & 0x3F);37
} else {38
break;39
}40
}41
return result;42
};43
44
45
// Usage example:46
47
const bytes = toBytes('Some text here...'); // converts string to UTF-8 bytes48
49
console.log(bytes); // [83, 111, 109, 101, 32, 116, 101, 120, 116, 32, 104, 101, 114, 101, 46, 46, 46]
