I have the following regex test on a users input:
function validate_form() {
return /^[a-fA-F0-9]+$/.test(document.form.input.value);
}
I the users input failed to meet the criteria, then how would i get an alert put in this code to inform them?
You could replace the return
statement with:
var isValid = /^[a-fA-F0-9]+$/.test(document.form.input.value);
if (!isValid) alert("Your value was invalid.");
return isValid;
Alternatively, you could keep your validation function as above, and do:
if (!validate_form()) alert("Your value was invalid.");
If you want to show the error message in the document itself, then you could do something like, and replace alert()
above with error()
:
function error(message) {
document.getElementById("error").innerHTML = message;
}
This assumes that you have an element in your HTML with id="error"
eg:
<div id="error"></div>
function validate_form() {
var alphanumeric = /^[a-fA-F0-9]+$/.test(document.form.input.value);
if(!alphanumeric){ alert("Silly human, you cannot use punctuation here!"); }
return alphanumeric;
}
function validate_form() {
return (/^[a-fA-F0-9]+$/.test(document.form.input.value)) ? "":alert("There is a problem with your input");
}
Working Example: http://jsfiddle.net/Q9qVU/
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.