Javascript implementation of convolution function

conv.js

/* Returns the discrete, linear convolution of two vectors.
** Convolution in time/space is equivalent to multiplication in the frequency domain.

This function is equivalent to numpy's convolve function with the default 'full' parameter

example :
------
vec1 = [2,3,4]
vec2 = [1,2,3]

multiply vec2 by vec1[0] = 2    4   6
multiply vec2 by vec1[1] = -    3   6   9
multiply vec2 by vec1[2] = -    -   4   8   12
-----------------------------------------------
add the above three      = 2    7   16  17  12

convolve(vec1, vec2) // [2,7,16,17,12]
**
*/

const convolve = (vec1, vec2) => {
  if (vec1.length === 0 || vec2.length === 0) {
    throw new Error("Vectors can not be empty!");
  }
  const volume = vec1;
  const kernel = vec2;
  let displacement = 0;
  const convVec = [];

  for (let i = 0; i < volume.length; i++) {
    for (let j = 0; j < kernel.length; j++) {
      if (displacement + j !== convVec.length) {
        convVec[displacement + j] =
          convVec[displacement + j] + volume[i] * kernel[j];
      } else {
        convVec.push(volume[i] * kernel[j]);
      }
    }
    displacement++;
  }

  return convVec;
};

Slightly optimized version:

const convolve = (vec1, vec2) => {
    if (vec1.length === 0 || vec2.length === 0) {
        throw new Error('Vectors can not be empty!');
    }
    const volume = vec1;
    const kernel = vec2;
    /* Initialized to zero by default */
    const convVec = new Float32Array(volume.length + kernel.length);

    let i = 0;
    for (let j = 0; j < kernel.length; ++j) {
        convVec[j] = volume[0] * kernel[j];
    }

    for (i = 1; i < volume.length; ++i) {
        for (let j = 0; j < kernel.length; ++j) {
            convVec[i + j] += volume[i] * kernel[j];
        }
    }

    return convVec;
};