chrome-devtools-frontend
Version:
Chrome DevTools UI
34 lines (30 loc) • 1.32 kB
text/typescript
// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
const BASE64_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
const BASE64_CODES = new Uint8Array(123);
for (let index = 0; index < BASE64_CHARS.length; ++index) {
BASE64_CODES[BASE64_CHARS.charCodeAt(index)] = index;
}
/**
* Decodes Base64-encoded data from a string without performing any kind of checking.
*/
export function decode(input: string): ArrayBuffer {
let bytesLength = ((input.length * 3) / 4) >>> 0;
if (input.charCodeAt(input.length - 2) === 0x3d /* '=' */) {
bytesLength -= 2;
} else if (input.charCodeAt(input.length - 1) === 0x3d /* '=' */) {
bytesLength -= 1;
}
const bytes = new Uint8Array(bytesLength);
for (let index = 0, offset = 0; index < input.length; index += 4) {
const a = BASE64_CODES[input.charCodeAt(index + 0)];
const b = BASE64_CODES[input.charCodeAt(index + 1)];
const c = BASE64_CODES[input.charCodeAt(index + 2)];
const d = BASE64_CODES[input.charCodeAt(index + 3)];
bytes[offset++] = (a << 2) | (b >> 4);
bytes[offset++] = ((b & 0x0f) << 4) | (c >> 2);
bytes[offset++] = ((c & 0x03) << 6) | (d & 0x3f);
}
return bytes.buffer;
}