如何检查多少未定义的dojo或JavaScript？ [英] How to check for multiple undefined in dojo or JavaScript?

问题描述

我的项目中有下面的代码段。正如你所看到的，我不得不检查未定义的所有对象和属性 this.view&& this.view.formView&& this.view.formView._dapSections&&& this.view.formView._dapSections.scrollTop 。

我正在寻找一种检查未定义的方法，在JavaScript或dojo中有任何方法吗？

  if（this.view&& this.view.formView& amp; this.view.formView._dapSections&& this.view.formView ._dapSections.scrollTop）{
 globals.lastScrollPosition = this.view.formView._dapSections.scrollTop; 
} 
  

解决方案

您可能还想尝试lang.exists（）
https://dojotoolkit.org/reference-guide/1.10/dojo/_base/lang.html#dojo-base-lang-exists

  if（lang.exists（'view.view.formView._dapSections.scrollTop'，this）{
 globals.lastScrollPosition = this.view.formView._dapSections.scrollTop; 
 
  

I have the below piece of code in my project. As you can see, I had to check the undefined for all the object and properties this.view && this.view.formView && this.view.formView._dapSections && this.view.formView._dapSections.scrollTop.

I'm looking for a way to check undefined for all at once.Is there any way to do that in JavaScript or dojo?

if(this.view && this.view.formView && this.view.formView._dapSections && this.view.formView._dapSections.scrollTop) {
                globals.lastScrollPosition = this.view.formView._dapSections.scrollTop;
            }

解决方案

You might also want to try lang.exists() https://dojotoolkit.org/reference-guide/1.10/dojo/_base/lang.html#dojo-base-lang-exists

if (lang.exists('view.view.formView._dapSections.scrollTop', this) {
    globals.lastScrollPosition = this.view.formView._dapSections.scrollTop;
}

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