html2canvas(document.body).then(function(canvas) {} 不调用

Question

我想在buttonbuttonclick上的javaScript函数中调用html2canvas(document.body).then(function(canvas){});。

工作代码：

function action () {
    if (elementScope == "body") {
         alert("generating pdf.........2");
         //alert("canvas........."+canvas)

        alert("document.body......."+document.body)
        //mypdf();
        html2canvas(document.body).then(function(canvas){
            alert("html2canvas called...!!!");
            var imageFullQuality = canvas.toDataURL();
            var docDefinition = {
                content: [{
                    image : imageFullQuality,
                    width : widthCanvas,
                }]
        };
        alert("generating pdf.........4");
        new  pdfMake.createPdf(docDefinition).download(fileName + ".pdf");
        });
    }
}

错误代码

html2canvas(document.body).then(function(canvas){});没有得到调用，剩余的代码将正常执行。

this.action = function action() {
    if (elementScope == "body") {
         alert("generating pdf.........2");
         //alert("canvas........."+canvas)

        alert("document.body......."+document.body)
        //mypdf();
        html2canvas(document.body).then(function(canvas){
            alert("html2canvas called...!!!");
            var imageFullQuality = canvas.toDataURL();
            var docDefinition = {
                content: [{
                    image : imageFullQuality,
                    width : widthCanvas,
                }]
            };
            alert("generating pdf.........4");
            new  pdfMake.createPdf(docDefinition).download(fileName + ".pdf");
        });
    }
}

这里没有什么问题。请帮帮我。

Answer 1

您可以直接分配函数而不是分配function action() {}

this.action => () {
    if (elementScope == "body") {
         alert("generating pdf.........2");
         //alert("canvas........."+canvas)

        alert("document.body......."+document.body)
        //mypdf();
        html2canvas(document.body).then(function(canvas){
            alert("html2canvas called...!!!");
            var imageFullQuality = canvas.toDataURL();
            var docDefinition = {
                content: [{
                    image : imageFullQuality,
                    width : widthCanvas,
                }]
            };
            alert("generating pdf.........4");
            new  pdfMake.createPdf(docDefinition).download(fileName + ".pdf");
        });
    }
}