How to add 'if' to jQuery chain code

问题

I need to replace the 4th line in -

this.menu = $("<ul>")
   .addClass("ui-autocomplete")
   .appendTo(this.document.find(this.options.appendTo || "body")[0])
   .zIndex(this.element.zIndex() + 1)  // !! <- here // !!
   .hide()
   .data("menu");

with the following code -

if (XXX.style.setProperty) {  // IE 9- does not support...
    XXX.style.setProperty ("z-index", (this???.element.zIndex() + 1), "important");
  }

• How do I merge this code?
• what is 'XXX' in my case?
• what is "this" ?

[relates to How to add 'important' to zIndex ]

回答1:

This should do it:

this.menu = $("<ul>")
  .addClass("ui-autocomplete")
  .appendTo(this.document.find(this.options.appendTo || "body")[0])
  .each(function() {
    this.style.cssText+= 'z-index: '+(parseInt($(this).css('z-index'))+1)+' !important';
  })
  .hide()
  .data("menu");

来源：https://stackoverflow.com/questions/30556847/how-to-add-if-to-jquery-chain-code