ReactJs选择添加默认值 [英] ReactJs Select add default value

问题描述

如果用户未在ReactJs中触摸它，我想存储选择默认值.那怎么可能?

I want to store select default value if user not touch it in ReactJs. How is that possible?

<select onChange={this.valSelected.bind(this)}>
    {currencies.map(function(name, index){
        return <option value={name}>{name}</option>;
    })}
</select>

和

valSelected(event){
    this.setState({
        valSelected: event.target.value
    });
}

推荐答案

您只需将value属性添加到select元素(由您的状态设置)即可.

You can just add a value property to the select element, set by your state.

<select value={this.state.valSelected} onChange={this.valSelected.bind(this)}>
    {currencies.map(function(name, index){
        return <option value={name}>{name}</option>;
    })}
</select>

此处在react docs中进行了描述:文档链接

This is described here in the react docs: Doc Link

然后在构造函数中或使用getInitialState为组件设置默认状态:

Then set a default state for the component, either in the constructor or with getInitialState: What is the difference between using constructor vs getInitialState in React / React Native?

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