所以我要在另一个文件夹中调用一个函数，该文件夹将继续并下载一个库（jsPDF），然后运行生成的代码。但是，每当我单击触发函数调用的按钮时，脚本就会被添加到头部，最终导致程序无法运行。我试图只添加一次脚本，如果添加了脚本，则不要添加脚本，而是继续其余代码。
调用运行功能
var myBtn = document.getElementById('submit1');
//add event listener
myBtn.addEventListener('click', function(event) {
fetch()
});
async function fetch(){
const itemToStore = document.getElementsByClassName("itemName");
const itemQty = document.getElementsByClassName("quoteQty");
const itemPrices = document.getElementsByClassName("quotePrice");
const itemTotal = document.getElementsByClassName("quoteTotal");
const totalCost = "Total Cost" + ":" + document.getElementById("quoteTotalCost").innerText;
fn(itemToStore, itemQty, itemPrices, itemTotal, totalCost)
// getFile()
}
Js代码
async function functionCall(){
var scripts = document.getElementsByTagName("script");
for(var i = 0; i < scripts.length; i++){
if(scripts[i].getAttribute('src') == 'https://cdnjs.cloudflare.com/ajax/libs/jspdf-autotable/2.0.28/jspdf.plugin.autotable.js'){
console.log('found once')
break;
}
else{
console.log('not found')
var jQueryScript = document.createElement('script');
var pdfScript = document.createElement('script');
var tableScript = document.createElement('script');
var actualTable = document.createElement('script');
jQueryScript.setAttribute('src','https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js');
pdfScript.setAttribute('src','https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.3.5/jspdf.debug.js');
tableScript.setAttribute('src','https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.2.61/jspdf.debug.js');
actualTable.setAttribute('src', 'https://cdnjs.cloudflare.com/ajax/libs/jspdf-autotable/2.0.28/jspdf.plugin.autotable.js');
document.head.appendChild(jQueryScript);
document.head.appendChild(pdfScript);
document.head.appendChild(tableScript);
document.head.appendChild(actualTable);
break;
}
}
return true;
}
function fn(a,b,c,e,f) {
functionCall().then(() => {
//rest of the code
错误消息
("jQuery.Deferred exception: doc.autoTable is not a function TypeError: doc.autoTable is not a function")
还有一条错误消息“ .then未定义”。