JavaScript webaudio to wav encoder

javascript.js

class WavAudioEncoder {

  encode = buffer => {
    const channelData = buffer.getChannelData(0);
    const length = buffer.length;
    const data = []
    for (let i = 0; i < length; ++i) { 
      let x = channelData[i] * 0x7fff;
      data.push(Math.round(x < 0 ? Math.max(x, -0x8000) : Math.min(x, 0x7fff)));
    }
    return this.interpolateArray(data, 16000, buffer.sampleRate);
  }

  interpolateArray = (data, newSampleRate, oldSampleRate) => {
    var fitCount = Math.round(data.length*(newSampleRate/oldSampleRate));
    var newData = new Array();
    var springFactor = new Number((data.length - 1) / (fitCount - 1));
    newData[0] = data[0]; // for new allocation
    for ( var i = 1; i < fitCount - 1; i++) {
      var tmp = i * springFactor;
      var before = new Number(Math.floor(tmp)).toFixed();
      var after = new Number(Math.ceil(tmp)).toFixed();
      var atPoint = tmp - before;
      newData[i] = this.linearInterpolate(data[before], data[after], atPoint);
    }
    newData[fitCount - 1] = data[data.length - 1]; // for new allocation
    return newData;
  }

  linearInterpolate = (before, after, atPoint) => {
    return Math.ceil(before + (after - before) * atPoint);
  }

}

export default WavAudioEncoder;

python.py

# having recieved `samples` through a websocket...

import struct

audio = struct.pack("<%dh" % len(samples), *samples)