Angularjs drop-down box blank solution

Search for the blank angularjs drop-down box, and many solutions can appear. However, for static fields, there is currently no solution found online, as follows:

1 <select class="form-control" ng-model="UserState"2         ng-init="UserState=0">3     <option value="-1">选择状态</option>4     <option value="0">在职</option>5     <option value="1">离职</option>6 </select>

If you want to follow the online To solve the problem, you first need to store the drop-down options in an object array. It's okay for one or two drop-down boxes. If there are many such drop-down boxes in the project, it will take a lot of effort. The simplest and crudest method is to modify the angularjs source code so that whitespace characters are no longer generated. However, my ability is limited and I couldn't find the place to add blank lines. However, it is gratifying to find that the blank characters appear because of the use of ng-model. Simply write an instruction to replace the function of ng-model, which can also solve the problem of drop-down blanks. problem, so I wrote an instruction:

app.directive("dModel",function () { 2       return { 3         restrict:'A', 4             compile:function(element, attrs, transclude){ 5 console.log (transclude); 6 var dmodel = Attrs ["dmodel"]; 7 Return {8 Pre: Function (scope, ielement, ictrs) {9 10 VAR SelectValue = scope [dmodel]+"" "; 11 if (selectvalue 12                                                                               options[i ].setAttribute("selected",true);19                                                                               break; }22                                                                                                                                               ("change",function () {26                     var selectValue=this.value;27 scope.$apply(function () {28 scope[dModel]= selectValue;29 );30
　

　　 用该指令替代ng-model即可实现相同的功能，同时不会出现下拉空白，当然，这个指令毕竟是自己随便写的几行代码，远远不如ng-model强大，比如动态修改指令绑定的值来改变选中项还不能实现，仅仅可以在第一次初始化时绑定选中项，另外也不支持ng-selected。如果读者有兴趣，可以自己实现后续的功能，对于我来说，已经可以满足需要了。

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