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mathjs

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Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

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'use strict'; const {PassThrough: PassThroughStream} = require('stream'); module.exports = options => { options = {...options}; const {array} = options; let {encoding} = options; const isBuffer = encoding === 'buffer'; let objectMode = false; if (array) { objectMode = !(encoding || isBuffer); } else { encoding = encoding || 'utf8'; } if (isBuffer) { encoding = null; } const stream = new PassThroughStream({objectMode}); if (encoding) { stream.setEncoding(encoding); } let length = 0; const chunks = []; stream.on('data', chunk => { chunks.push(chunk); if (objectMode) { length = chunks.length; } else { length += chunk.length; } }); stream.getBufferedValue = () => { if (array) { return chunks; } return isBuffer ? Buffer.concat(chunks, length) : chunks.join(''); }; stream.getBufferedLength = () => length; return stream; };