$("#downpdf").on("click", function () {

document.body.scrollTop=document.documentElement.scrollTop=0

var id=‘task_report‘;

html2canvas($("#"+id), {

scale:2,

background: "#FFFFFF",//如果指定的div没有设置背景色会默认成黑色,这里是个坑

onrendered:function(canvas) {

//未生成pdf的html页面高度

var leftHeight = canvas.height;

var a4Width = 190

var a4Height = 277 //A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277

//一页pdf显示html页面生成的canvas高度;

var a4HeightRef = Math.floor(canvas.width / a4Width * a4Height);

//pdf页面偏移

var position = 0;

var pageData = canvas.toDataURL(‘image/jpeg‘, 1.0);

var pdf = new jsPDF(‘p‘, ‘mm‘, ‘a4‘); //A4纸，纵向

var index = 1,

canvas1 = document.createElement(‘canvas‘),

height;

pdf.setDisplayMode(‘fullwidth‘, ‘continuous‘, ‘FullScreen‘);

var pdfName=‘TriButte漏洞管理平台扫描报告‘;

function createImpl(canvas) {

console.log(leftHeight,a4HeightRef)

if (leftHeight > 0) {

index++;

var checkCount = 0;

if (leftHeight > a4HeightRef) {

var i = position + a4HeightRef;

for (i = position + a4HeightRef; i >= position; i--) {

var isWrite = true

for (var j = 0; j < canvas.width; j++) {

var c = canvas.getContext(‘2d‘).getImageData(j, i, 1, 1).data

if (c[0] != 0xff || c[1] != 0xff || c[2] != 0xff) {

isWrite = false

break

}

}

if (isWrite) {

checkCount++

if (checkCount >= 10) {

break

}

} else {

checkCount = 0

}

}

height = Math.round(i - position) || Math.min(leftHeight, a4HeightRef);

if(height<=0){

height = a4HeightRef;

}

} else {

height = leftHeight;

}

canvas1.width = canvas.width;

canvas1.height = height;

console.log(index, ‘height:‘, height, ‘pos‘, position);

var ctx = canvas1.getContext(‘2d‘);

ctx.drawImage(canvas, 0, position, canvas.width, height, 0, 0, canvas.width, height);

var pageHeight = Math.round(a4Width / canvas.width * height);

// pdf.setPageSize(null, pageHeight)

if(position != 0){

pdf.addPage();

}

pdf.addImage(canvas1.toDataURL(‘image/jpeg‘, 1.0), ‘JPEG‘, 10, 10, a4Width, a4Width / canvas1.width * height);

leftHeight -= height;

position += height;

if (leftHeight > 0) {

setTimeout(createImpl, 500, canvas);

} else {

pdf.save(pdfName + ‘.pdf‘);

}

}

}

//当内容未超过pdf一页显示的范围，无需分页

if (leftHeight < a4HeightRef) {

pdf.addImage(pageData, ‘JPEG‘, 0, 0, a4Width, a4Width / canvas.width * leftHeight);

pdf.save(pdfName + ‘.pdf‘)

} else {

try {

pdf.deletePage(0);

setTimeout(createImpl, 500, canvas);

} catch (err) {

// console.log(err);

}

}

}

})

});

原文：https://www.cnblogs.com/ellisonzhang/p/12851068.html