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DJB2 hash in JavaScript (32-bit version)
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| <html> | |
| <body> | |
| <h2>32-bit DJB2 hash in JavaScript demo</h2> | |
| <input type="file" id="file-input" /> | |
| <h3 id="result">Select file to calculate DJB2 hash</h3> | |
| </body> | |
| <script> | |
| // DJB2 hash function. Takes ArrayBuffer | |
| function hash_buf_djb2_32(buf) { | |
| var hash = 5381; | |
| let view = new Uint8Array(buf); | |
| for (let num of view) | |
| hash = ((hash << 5) + hash + num) & 0xFFFFFFFF; | |
| return hash >>> 0; | |
| } | |
| function readSingleFile(e) { | |
| var file = e.target.files[0]; | |
| if (!file) { | |
| return; | |
| } | |
| var reader = new FileReader(); | |
| reader.onload = function(e) { | |
| var contents = e.target.result; | |
| displayContents(contents); | |
| }; | |
| reader.readAsArrayBuffer(file); | |
| } | |
| function displayContents(contents) { | |
| var element = document.getElementById('result'); | |
| element.textContent = "Hash = " + hash_buf_djb2_32(contents) + ", Len = " + contents.byteLength; | |
| } | |
| document.getElementById('file-input') | |
| .addEventListener('change', readSingleFile, false); | |
| </script> | |
| </html> |
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| // 32-bit DJB2 hash in JavaScript | |
| // DJB2 is probably the simplest among relatively good checksum and hash functions. | |
| // DJB2 outperforms CRC32 in speed and comes close to it in performance. | |
| // You should still use CRC32, especially if your CPU supports CRC calculation natively. | |
| // On 32-bit or 64-bit architectures, MurmurHash can outperform DJB2. | |
| // Takes ArrayBuffer | |
| function hash_buf_djb2_32(buf) { | |
| var hash = 5381; | |
| let view = new Uint8Array(buf); | |
| for (let num of view) | |
| hash = ((hash << 5) + hash + num) & 0xFFFFFFFF; | |
| return hash >>> 0; | |
| } | |
| // Takes string (NOTE: charCode can be larger than 255) | |
| function hash_str_djb2_32(str) { | |
| var len = str.length; | |
| var hash = 5381; | |
| for (var idx = 0; idx < len; ++idx) { | |
| hash = ((hash << 5) + hash + str.charCodeAt(idx)) & 0xFFFFFFFF; | |
| } | |
| return hash >>> 0; | |
| } |
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