页面加载后，输入类型验证第一次不起作用

Question

I have a text box, in that I wants to allow only alphabets.

Below is my code :

state ={
    NomName: '',
}

onlyAlpha(e) {
    var regex = /^[a-zA-Z ]*$/;
    if(e.target.value === '' || regex.test(e.target.value)) {
        this.setState({NomName:e.target.value})
    }
}


render = () => {
    return (
        <label for="nominee">Nominee name</label>
        <input type="text" value={this.state.NomName} id="nominee" class="form-control"
        onChange={this.onlyAlpha.bind(this)} autoComplete="off"
        maxLength="100"/>
)}

The input validations are not working (I am able to enter Numbers) at very first time after page loads. But once you cleared the field and try to re-enter the value it won't takes numbers (It works).

How can I make it run at each and every time.?

Please let me know if I am doing anything wrong.

Answer 1

I suggest you start using fat arrow functions. Make the onlyAlpha function like so:

onlyAlpha = (e) => {
    var regex = /^[a-zA-Z ]*$/;
    if(e.target.value === '' || regex.test(e.target.value)) {
        this.setState({NomName:e.target.value})
    }
}

This would remove the usage of this.onlyAlpha.bind(this) .

Also, I think you should pass the function to the onChange listener like so:

<input type="text" value={this.state.NomName} id="nominee" class="form-control"
    onChange={this.onlyAlpha} autoComplete="off"
    maxLength="100"/>