电子邮件Javascript验证消息

Question

I would like a message to be shown to the user, if an email address is entered incorrectly.

Html

<p>Email: <input type="email" id="email" onblur="validateEmail()" 
required>

<p id="emailMessage"></p>

Javascript

function validateEmail(email){
    var regEx = /\S+@\S+/;
    var result = regEX.test(email);

    if (result = true)
        document.getElementById("emailMessage").innerhtml = ""
    else (result = false)
        document.getElementById("emailMessage").innerhtml = "Please enter a valid 
email address"
}

Answer 1

There are many issues in your approach. Because you seems to be new to this, I will tell you what is wrong step-by-step:

• result = true and result = false will set the value of result to a boolean. A condition has to be == or === . Or in your case, just use the result variable, what is already an boolean because of the result of .test() .
• Use innerHTML instead of innerhtml .
• It's not allowed to break a string in javascript like this.
• Your variable is called regEx not regEX .
• email is not a parameter of the function by default, you need to pass this to the function to have it available.
• You need to check on email.value , nut just email , beacuse this is just the element.
• else can't have a condition to check, if you want to you need to use else if , but that is not needed here.

 function validateEmail(email) { var regEx = /\\S+@\\S+/; var result = regEx.test(email.value); if (result) { document.getElementById("emailMessage").innerHTML = ""; } else { document.getElementById("emailMessage").innerHTML = "Please enter a valid email address"; } } 

 <p>Email:</p> <input type="email" id="email" onblur="validateEmail(this)" required> <p id="emailMessage"></p> 

Answer 2

//correct code
  function validateEmail(email)
     {
      var regEx = /\S+@\S+/;
      var result = regEX.test(email);
      if (result == true)
          document.getElementById("emailMessage").innerHTML = ""
      else (result == false)
          document.getElementById("emailMessage").innerHTML = "Please enter a valid email address"
}

Answer 3

document.getElementById("emailMessage").innerHTML = "Please enter a valid 
email address"

//use innerHTML not innerhtml, that is the problem