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86d333ee94
* chore: Switch to Node 20 + Vitest * chore: migrate to vitest mock functions * chore: code style (switch to prettier) * test: re-enable long-running test Seems the switch to Node 20 and Vitest has vastly improved the code's and / or the test's runtime! see #1193 * chore: code style * chore: fix failing tests * Updated Documentation in README.md * Update contribution guidelines to state usage of Prettier * fix: set prettier printWidth back to 80 * chore: apply updated code style automatically * fix: set prettier line endings to lf again * chore: apply updated code style automatically --------- Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>
49 lines
1.9 KiB
JavaScript
49 lines
1.9 KiB
JavaScript
// About base64: https://en.wikipedia.org/wiki/Base64
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/**
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* Converts a base64 string to an array of bytes
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* @param {string} b64 A base64 string
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* @returns {ArrayBuffer} An ArrayBuffer representing the bytes encoded by the base64 string
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*/
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function base64ToBuffer(b64) {
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// The base64 encoding uses the following set of characters to encode any binary data as text
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const base64Table =
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
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// Find the index of char '=' first occurrence
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const paddingIdx = b64.indexOf('=')
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// Remove padding chars from base64 string, if there are any
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const b64NoPadding = paddingIdx !== -1 ? b64.slice(0, paddingIdx) : b64
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// Calculate the length of the result buffer
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const bufferLength = Math.floor((b64NoPadding.length * 6) / 8)
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// Create the result buffer
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const result = new ArrayBuffer(bufferLength)
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// Create an instance of Uint8Array, to write to the `result` buffer
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const byteView = new Uint8Array(result)
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// Loop through all chars in the base64 string, in increments of 4 chars, and in increments of 3 bytes
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for (let i = 0, j = 0; i < b64NoPadding.length; i += 4, j += 3) {
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// Get the index of the next 4 base64 chars
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const b64Char1 = base64Table.indexOf(b64NoPadding[i])
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const b64Char2 = base64Table.indexOf(b64NoPadding[i + 1])
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let b64Char3 = base64Table.indexOf(b64NoPadding[i + 2])
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let b64Char4 = base64Table.indexOf(b64NoPadding[i + 3])
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// If base64 chars 3 and 4 don't exit, then set them to 0
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if (b64Char3 === -1) b64Char3 = 0
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if (b64Char4 === -1) b64Char4 = 0
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// Calculate the next 3 bytes
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const byte1 = (b64Char1 << 2) + ((b64Char2 & 48) >> 4)
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const byte2 = ((b64Char2 & 15) << 4) + ((b64Char3 & 60) >> 2)
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const byte3 = ((b64Char3 & 3) << 6) + b64Char4
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byteView[j] = byte1
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byteView[j + 1] = byte2
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byteView[j + 2] = byte3
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}
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return result
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}
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export { base64ToBuffer }
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