我可以从下拉选择变量中删除“null"吗 [英] Can I remove 'null' from my drop down selection variable

问题描述

我有一个多选下拉菜单，允许我的用户使用 react-select 选择多个 A、B 和/或 C 选项.每次选择一个时，我都希望将其添加到选择"变量中以进行记录.我有这个工作，但因为我必须先声明我的变量，它在变量中保存了 'null'.我该如何摆脱这个?代码如下.

I have a multi select drop down allowing my user to select multiple A, B and/or C options, using react-select. Each time one is selected, I want it to be added to a 'choice' variable to keep record. I have this working, but since I have to declare my variable first, it is holding 'null' inside the variable. How do I get rid of this? Code below.

handleChange = (selectedChoice) => {
this.setState({ selectedChoice });
for (var i =0; i < selectedChoice.length; i++) {
   var filter = null;
   filter +=(selectedChoice[i].value); //removing the plus just resets it to last chosen option
    }
  console.log(filter);
  }

打印内容示例:nullAC

example of what it prints: nullAC

推荐答案

此问题的解决方案由 Yury 在评论中发布塔拉班科.

The solution to this was posted in the comments by Yury Tarabanko.

var filter = ''

为了良好的实践，console.log 也不会在代码中的那个位置.

For good practice console.log would also not be in that position within the code.

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