javascript - Javascript工作者接收消息永远不会被调用

Question

function receiveMessage(e) {
    alert("received message");
    if (e.data.success === "log") {
        console.log(e.data.result);
       return;
   }
    if (e.data.finished) {
        workerCount--;
        if (workerCount) {
            if (resultArray.length == 0) {
                DecodeWorker.postMessage({ ImageData: ctx.getImageData(0, 0, Canvas.width, Canvas.height).data, Width: Canvas.width, Height: Canvas.height, cmd: "flip", Decode: "Code39"});
            } else {
                workerCount--;
            }
        }
    }
    if (e.data.success) {
        var tempArray = e.data.result;
        for (var i = 0; i < tempArray.length; i++) {
            if (resultArray.indexOf(tempArray[i]) == -1) {
                resultArray.push(tempArray[i]);
            }
        }
        alert(resultArray[0]);
    } else {
        if (resultArray.length === 0 && workerCount === 0) {
            alert("Decoding failed.");
        }
    }
}

var DecodeWorker = new Worker("js/BarcodeScanner.js");
DecodeWorker.onmessage = receiveMessage;
// Called when a photo is successfully retrieved
//
function onPhotoDataSuccess(imageData) {
    // Uncomment to view the base64 encoded image data
    // console.log(imageData);
    smallPicture = document.getElementById('smallImage');
    // Get image handle
    //

    // Unhide image elements
    //
    smallPicture.style.display = 'block';

    // Show the captured photo
    // The inline CSS rules are used to resize the image
    //
    smallPicture.onload = function () {
        ctx.drawImage(smallPicture, 0, 0, Canvas.width, Canvas.height);


        resultArray = [];

        workerCount = 2;
        alert("Prepost");
        barcodeNum("");
        alert("Post");
        DecodeWorker.postMessage({ ImageData: ctx.getImageData(0, 0, Canvas.width, Canvas.height).data, Width: Canvas.width, Height: Canvas.height, cmd: "normal", Decode: "Code39" });
};


    smallPicture.src = "data:image/jpeg;base64," + imageData;
}

在我的 decodeWorker 上使用 postMessage 函数时，永远不会调用 receiveMessage 函数，而且我无法弄清楚我做错了什么，似乎最坏的情况我至少会看到“收到的消息”警报我设置的，但即使这样也不会发生。