mirror of
https://git.sr.ht/~emersion/gamja
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42 lines
1.2 KiB
JavaScript
42 lines
1.2 KiB
JavaScript
const alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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/* The JS world is still in the stone age. We're in 2022 and we still don't
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* have the technology to correctly base64-encode a UTF-8 string. Can't wait
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* the next industrial revolution.
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*
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* For more info, see:
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* https://developer.mozilla.org/en-US/docs/Glossary/Base64#the_unicode_problem
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*/
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export function encode(data) {
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if (!window.TextEncoder) {
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return btoa(data);
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}
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let encoder = new TextEncoder();
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let bytes = encoder.encode(data);
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let trailing = bytes.length % 3;
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let out = "";
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for (let i = 0; i < bytes.length - trailing; i += 3) {
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let u24 = (bytes[i] << 16) + (bytes[i + 1] << 8) + bytes[i + 2];
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out += alphabet[(u24 >> 18) & 0x3F];
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out += alphabet[(u24 >> 12) & 0x3F];
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out += alphabet[(u24 >> 6) & 0x3F];
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out += alphabet[u24 & 0x3F];
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}
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if (trailing == 1) {
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let u8 = bytes[bytes.length - 1];
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out += alphabet[u8 >> 2];
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out += alphabet[(u8 << 4) & 0x3F];
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out += "==";
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} else if (trailing == 2) {
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let u16 = (bytes[bytes.length - 2] << 8) + bytes[bytes.length - 1];
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out += alphabet[u16 >> 10];
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out += alphabet[(u16 >> 4) & 0x3F];
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out += alphabet[(u16 << 2) & 0x3F];
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out += "=";
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}
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return out;
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}
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