Question

我正在尝试检查空值，即使我知道值为null，循环仍然不会中断。为任何帮助干杯

constructor(){
    super();
    this.state = {
        warningMsg: 'No Warnings'
    }
    this.detail = {
        name: null,
        phone: null,
        email: null,
        location: null,
        extraDetail: 'Default' 
    }
}

handleSubmit(){
    const {DetailStore} = this.props;

    for (let value in this.detail) {
        console.log(value)
        if (value === null) {
            console.log('null found'); // i should see this in console but i don't
            this.setState({warningMsg:'Check Input'});
            break;
        }
    }
    DetailStore.entDetail(this.detail);
    console.log(DetailStore.getDetail,'Submitted'); 
}

Answer 1

for..in循环遍历对象的属性名称，而不是属性的值。如果要迭代对象值，最好使用Object.values代替：

if (Object.values(this.detail).some(value => value === null)) {
  console.log('null found');
  this.setState({warningMsg:'Check Input'});
}

Answer 2

＆＃39;价值＆＃39;在你的for循环中实际上是属性名称。你需要检查： if (this.detail[value] === null)

你真正想要的是：

＆＃13;

const detailValues = Object.values(this.detail);

for (const value of detailValues) {
  console.log(value)
  if (value === null) {
    console.log('null found'); // i should see this in console but i don't
    this.setState({
      warningMsg: 'Check Input'
    });
    break;
  }
}

＆＃13;

空检查对象无效

2 个答案: