Question

在绘制数据驱动网格的页面底部附近，网格包具有此代码......

<script type="text/javascript">
    (function(window, document, undefined) {
      "use strict";
      var gridColSortTypes = 
          ["string", "string", "number", "number", "number", "number", "number", "number", "number", "number"],
          gridColAlign = [];
      var onColumnSort = function( newIndexOrder, columnIndex, lastColumnIndex ) {
        var doc = document;
        var offset = (this.options.allowSelections && this.options.showSelectionColumn)?1:0;
        if( columnIndex !== lastColumnIndex ) {
          if( lastColumnIndex > -1 ) {
            doc.getElementById("stockHdr" + (lastColumnIndex-offset)).parentNode.style.backgroundColor = "";
          }
          doc.getElementById("stockHdr" + (columnIndex-offset)).parentNode.style.backgroundColor = "#f7f7f7";
        }
      };
      ...
})(this, this.document);

调查指定排序列颜色更改失败的原因，我发现尽管getElementById（）查询的对象存在且在页面中正常运行，但在此函数内，这些getElementById（）调用返回Null。实际上，从此函数调用的所有getElementById（）调用都返回Null。

为什么？

Answer 1

当您尝试访问DOM内容时，我会假设DOM内容尚未就绪/可访问，请尝试将代码包装在window.onload中：

window.onload = function(){
  (function(window, doc, undefined) {
      "use strict";
      var gridColSortTypes = 
          ["string", "string", "number", "number", "number", "number", "number", "number", "number", "number"],
          gridColAlign = [];
      var onColumnSort = function( newIndexOrder, columnIndex, lastColumnIndex ) {
        var offset = (this.options.allowSelections && this.options.showSelectionColumn)?1:0;
        if( columnIndex !== lastColumnIndex ) {
          if( lastColumnIndex > -1 ) {
            doc.getElementById("stockHdr" + (lastColumnIndex-offset)).parentNode.style.backgroundColor = "";
          }
          doc.getElementById("stockHdr" + (columnIndex-offset)).parentNode.style.backgroundColor = "#f7f7f7";
        }
      };
      ...
   })(this, this.document);
};

getElementById（）为现有对象返回Null

1 个答案: