var progress = new FileProgress(file, this.customSettings.upload_target);解决办法 _JavaScript

var progress = new FileProgress(file, this.customSettings.upload_target);

问题1.
this.fileProgressID = "divFileProgress"; 中的this指的是什么？

问题2：
这是一个函数。下边好像是设置什么属性，不理解这种表达方式
FileProgress.prototype.setProgress = function (percentage) {
this.fileProgressElement.className = "progressContainer green";
this.fileProgressElement.childNodes[3].className = "progressBarInProgress";
this.fileProgressElement.childNodes[3].style.width = percentage + "%";
};

问题3：
var progress = new FileProgress(file, this.customSettings.upload_target);
这是一个函数，直接调用就行，为什么还要 new

不好意思问这么多，谢谢！

这是swfupload里边handle.js的东西

JScript code


/* ******************************************
 *    FileProgress Object
 *    Control object for displaying file info
 * ****************************************** */

function FileProgress(file, targetID) {
    this.fileProgressID = "divFileProgress";

    this.fileProgressWrapper = document.getElementById(this.fileProgressID);
    if (!this.fileProgressWrapper) {
        this.fileProgressWrapper = document.createElement("div");
        this.fileProgressWrapper.className = "progressWrapper";
        this.fileProgressWrapper.id = this.fileProgressID;

        this.fileProgressElement = document.createElement("div");
        this.fileProgressElement.className = "progressContainer";

        var progressCancel = document.createElement("a");
        progressCancel.className = "progressCancel";
        progressCancel.href = "#";
        progressCancel.style.visibility = "hidden";
        progressCancel.appendChild(document.createTextNode(" "));

        var progressText = document.createElement("div");
        progressText.className = "progressName";
        progressText.appendChild(document.createTextNode(file.name));

        var progressBar = document.createElement("div");
        progressBar.className = "progressBarInProgress";

        var progressStatus = document.createElement("div");
        progressStatus.className = "progressBarStatus";
        progressStatus.innerHTML = "&nbsp;";

        this.fileProgressElement.appendChild(progressCancel);
        this.fileProgressElement.appendChild(progressText);
        this.fileProgressElement.appendChild(progressStatus);
        this.fileProgressElement.appendChild(progressBar);

        this.fileProgressWrapper.appendChild(this.fileProgressElement);

        document.getElementById(targetID).appendChild(this.fileProgressWrapper);
        fadeIn(this.fileProgressWrapper, 0);

    } else {
        this.fileProgressElement = this.fileProgressWrapper.firstChild;
        this.fileProgressElement.childNodes[1].firstChild.nodeValue = file.name;
    }

    this.height = this.fileProgressWrapper.offsetHeight;

}
FileProgress.prototype.setProgress = function (percentage) {
    this.fileProgressElement.className = "progressContainer green";
    this.fileProgressElement.childNodes[3].className = "progressBarInProgress";
    this.fileProgressElement.childNodes[3].style.width = percentage + "%";
};
FileProgress.prototype.setComplete = function () {
    this.fileProgressElement.className = "progressContainer blue";
    this.fileProgressElement.childNodes[3].className = "progressBarComplete";
    this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setError = function () {
    this.fileProgressElement.className = "progressContainer red";
    this.fileProgressElement.childNodes[3].className = "progressBarError";
    this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setCancelled = function () {
    this.fileProgressElement.className = "progressContainer";
    this.fileProgressElement.childNodes[3].className = "progressBarError";
    this.fileProgressElement.childNodes[3].style.width = "";

};
FileProgress.prototype.setStatus = function (status) {
    this.fileProgressElement.childNodes[2].innerHTML = status;
};

FileProgress.prototype.toggleCancel = function (show, swfuploadInstance) {
    this.fileProgressElement.childNodes[0].style.visibility = show ? "visible" : "hidden";
    if (swfuploadInstance) {
        var fileID = this.fileProgressID;
        this.fileProgressElement.childNodes[0].onclick = function () {
            swfuploadInstance.cancelUpload(fileID);
            return false;
        };
    }
};