var content = "[1][][1]";
        var reg = new RegExp("[1]", "g");
        var result = content.replace(reg, "a");
        //最终出来的结果应该是"a[]a"

 var reg = new RegExp("\\[1\\]", "g");

------解决方案--------------------
var reg = new RegExp("\\[1\\]", "g");


------解决方案--------------------
探讨

JScript code
 var reg = new RegExp("\\[1\\]", "g");


------解决方案--------------------
  var reg = /\[1\]/g;