How to validate RegExp with an if else statement in react?

Question

how to alert a user if the user types a symbol into a text input in react? I tried this

textChange = () => {
   if (this.state.texts == new RegExp(/[^a-zA-Z\s]/) ) {
       alert("No symbols allowed")
   }
}

but noting is alerting when a symbol is type

Try if( new RegExp(/[^a-zA-Z\s]/).test(this.state.texts) ) — User863
– User863, Commented Nov 15, 2019 at 5:32

Code Maniac · Accepted Answer · 2019-11-15 05:34:36Z

6

Instead of comparing the equality of string with the regex object, you need to use test method, which returns a boolean value based on the passed string matching pattern or not

textChange = () => {
   if (/[^a-zA-Z\s]/.test(this.state.text) ) {
      alert("No symbols allowed")
   }
}

answered Nov 15, 2019 at 5:34

Code Maniac

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Comments

BadPiggie · Accepted Answer · 2019-11-15 05:37:51Z

4

Use test or match methods,

textChange = () => {
   if (/[^a-zA-Z\s]/.test(this.state.text) ) {
      alert("No symbols allowed")
   }
}

or

textChange = () => {
   if (this.state.text.match(/[^a-zA-Z\s]/) !== null) {
      alert("No symbols allowed")
   }
}

answered Nov 15, 2019 at 5:37

BadPiggie

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Comments

Ajith · Accepted Answer · 2019-11-15 05:57:41Z

2

You can use text method of javascript to validate using regular expression.

textChange =  () => {

  const expression = /[^a-zA-Z\s]/;
  var notValid = expression.test(String(this.state.texts));
  // notValid will be true if entered text does'nt match the expression

  if(notValid){
    alert("No symbols allowed");
  }else{
    //Valid value
  }


}

answered Nov 15, 2019 at 5:57

Ajith

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