No error, but still not working...

[NoBodyButMe]

I have this code, can you explain why this doesn't show any result?

    var c = document.getElementById("c2");
    var ctx = c.getContext("2d");

    // Create gradient
    var grd = ctx.createLinearGradient(0, 0, 200, 0);
    grd.addColorStop(0, "red");
    grd.addColorStop(1, "white");

    // Fill with gradient
    ctx.fillStyle = grd;
    ctx.fillRect(10, 10, 150, 80);
         /*webassembly*/
        let wam;
        loadWASM()
          .then(module => {
            wam = module;
        }).catch((err) => {
          console.log('Error in fetching module: ', err);
        }).then(() => {
            window.onload = (() => {
                var pixels = ctx.getImageData(0, 0, 400, 300);
                //console.log(pixels);
                var xx = pixels.data.set(wam.goodMorning(pixels.data, 400, 300));
                //var xx = wam.goodMorning(pixels.data, 400, 300);
                //console.log(xx);
                pixels.data.set(xx);
            })();
        });