Even if I give the right Input it still showing the error alert message-CodePudding

This is the code

<div ><input id="name" type="text" placeholder="Name" name="name" ></div> <button type="submit" onclick="check()">Sign Up</button>

let first = document.getElementById('name');



function check() {
  var pattern = /^[a-zA-Z] $/;
  var res = pattern.test(first.value);
  
  if(first.value != res){
    alert('Invalid First Name');
  } 
  
}

I have tried keeping (first.value = res) and then executing. This time it is giving alert message only when there is correct input but not when wrong input. But as keep (first.value != res) then it is showing error message every time I press the signup button.

CodePudding user response：

The .test() method returns a boolean. You just need to check if the value matches the regex if not you can run the alert.

 let first = document.getElementById('name');
    
    
    function check() {
      var pattern = /^[a-zA-Z] $/;
      var res = pattern.test(first.value);
      console.log(first.value)
      
      if(!res){
        alert('Invalid First Name');
      } 
      
    }