动态显示select的option列表

文件名：dynamicShowOptionOfSelectInHtml.html

```html
<!DOCTYPE html>
<html lang="zh">

 <head>
  <meta charset="UTF-8">
  <title>动态显示select的option列表</title>
  <script>
    function extractKey(fieldname, item) {
        var text = "";
        var tmp_fieldname = fieldname;

if (beginIndex > endIndex) {
                return 'ERROR_' + fieldname;
            }
            var varname = tmp_fieldname.substring(beginIndex + ("{{".length), endIndex);
            console.log('varname', varname);
            tmp_fieldname = tmp_fieldname.replace("{{" + varname + "}}", item[varname]);
            console.log('tmp_fieldname', tmp_fieldname);
            beginIndex = tmp_fieldname.indexOf("{{");
        }
        return tmp_fieldname;
    }
    function convert(orgdata, textfield, valuefield) {
          var optionArr = [];
          for (item of orgdata) {
              var _name = "" + extractKey(textfield, item);
              var _value = "" + extractKey(valuefield, item);
//              var _name = "" + item[textfield];
//              var _value = "" + item[valuefield]
              optionArr.push({ key: _value, text: _name, value: _value, 'data-datasource': item });
          }
          return optionArr;
    }

var testDataArr = [
        {"id": 1, "name": "张三", "age": 11},
        {"id": 2, "name": "李四", "age": 23},
        {"id": 3, "name": "王五", "age": 56},
    ]

<br/>
  <select id='user'>
  </select>
 </body>
</html>
```