ReferenceError：标签未在 Dymo 框架中定义答案

【问题标题】：ReferenceError: label is not defined in Dymo frameworkReferenceError：标签未在 Dymo 框架中定义
【发布时间】：2015-10-11 21:38:34
【问题描述】：

我在玩Dymo 的 JS 框架。 original example 可以正常工作，但即使我不想点击它也会加载 XML。我只在调用它时才重写以执行 Dymo 代码：

<script type="text/javascript">
       function printnow() {              
               $.get("./cont.label", function(labelXml) {
               label = dymo.label.framework.openLabelXml(labelXml);
               }, "text");
               // open label
               // set label text
               label.setObjectText("MENO", "test");
               label.setObjectText("MUNKA", "test");
               label.setObjectText("DESCRIPTION", test);
               // select printer to print on
               // for simplicity sake just use the first LabelWriter printer
               var printers = dymo.label.framework.getPrinters();
               if (printers.length == 0) throw "No DYMO printers are installed. Install DYMO printers.";
               var printerName = "";
               for (var i = 0; i < printers.length; ++i) {
                   var printer = printers[i];
                   if (printer.printerType == "LabelWriterPrinter") {
                       printerName = printer.name;
                       break;
                   }
               }
               if (printerName == "") throw "No LabelWriter printers found. Install LabelWriter printer";
               // finally print the label
               label.print(printerName);

       };
</script>

不幸的是，在我调用 printnow(); 之后我得到ReferenceError: label is not defined 问题出在哪里？

【问题讨论】：

stackoverflow.com/questions/14220321/…
$.get() 调用是异步。在 HTTP 调用完成之前，变量 label 不会获得值，但 $.get() 调用本身会立即返回。将准备和打印内容的代码放入回调中。

标签： javascript dymo

【解决方案1】：

首先你必须阅读这个one。

简而言之，您正在处理异步代码。因此，这 label.setObjectText("MENO", "test"); 和其余代码将在此 label = dymo.label.framework.openLabelXml(labelXml); 行之前执行。

最后，你必须这样做：

<script type="text/javascript">
       function printnow() {              
               $.get("./cont.label", function(labelXml) {
               var label = dymo.label.framework.openLabelXml(labelXml);
               // open label
               // set label text
               label.setObjectText("MENO", "test");
               label.setObjectText("MUNKA", "test");
               label.setObjectText("DESCRIPTION", test);
               // select printer to print on
               // for simplicity sake just use the first LabelWriter printer
               var printers = dymo.label.framework.getPrinters();
               if (printers.length == 0) throw "No DYMO printers are installed. Install DYMO printers.";
               var printerName = "";
               for (var i = 0; i < printers.length; ++i) {
                   var printer = printers[i];
                   if (printer.printerType == "LabelWriterPrinter") {
                       printerName = printer.name;
                       break;
                   }
               }
               if (printerName == "") throw "No LabelWriter printers found. Install LabelWriter printer";
               // finally print the label
               label.print(printerName);

               }, "text");

       };
</script>

【讨论】：