To check if a string is a valid email address in JavaScript, we can use a regex expression to match the symbols like @
, .
and the strings in between them.
TL;DR
// Regular expression to check if string is email
const regexExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/gi;
// String with email address
const str = "[email protected]";
regexExp.test(str); // true
This is the regex expression for matching almost all the test cases for a valid email address in JavaScript.
// Regular expression to check if string is email
const regexExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/gi;
Now let's write a string with email address like this,
// Regular expression to check if string is email
const regexExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/gi;
// String with email address
const str = "[email protected]";
Now to test the string, we can use the test()
method available in the regular expression we defined. It can be done like this,
// Regular expression to check if string is email
const regexExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/gi;
// String with email address
const str = "[email protected]";
regexExp.test(str); // true
- The
test()
method will accept astring
type as an argument to test for a match. - The method will return boolean
true
if there is a match using the regular expression andfalse
if not.
See the above example live in JSBin.
If you want this as a utility function which you can reuse, here it is,
/* Check if string is email */
function checkIfEmail(str) {
// Regular expression to check if string is email
const regexExp = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/gi;
return regexExp.test(str);
}
// Use the function
checkIfEmail("[email protected]"); // true
checkIfEmail("johndoe@example."); // false
That's all! 😃