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How to validate Text Box to allow Specific URI?

i am developing application using Code-igniter.
I want to validate Text Box Using J Query Or JavaScript That only allowed to input following URL when user submit form.
http://
https://
ftp://
ftps://
file://
market://
linkedin://
fb://
geo:
maps://
Is there any way to do this ?

function is_url(str)
{
regexp = /^(?:(?:https?|ftps?|file?|market?|linkedin?|fb?|maps?):\/\/)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:\/\S*)?$/;
if (regexp.test(str))
{
return true;
}
else
{
return false;
}
}

Try using this regex in a function that checks validity of your input.
/^(http|https|ftp|ftps|file|market|linkedin|fb|maps|geo):\/\//g
But do the reverse logic:
if it matches then display error mesage and clear input.
If it not matches then your URL is fine
If you wanna prevent URLs anywhere in your input, remove the leading ^ in regex to match even if URL is not start of the string.
like: /(http|https|ftp|ftps|file|market|linkedin|fb|maps|geo):\/\//gm
Here is a crud version of entire solution:
fiddlejs
Main thing is URL validation:
$("#urlInput").focusout(function (){
var inputElement = $("#urlInput");
var regexp = /(http|https|ftp|ftps|file|market|linkedin|fb|maps|geo):\/\//gm;
if (regexp.test(inputElement.val())){
inputElement.val("");
alert("This is nto a valid URL")
}
});
It bound to the
<input id="urlInput" type="url">
You might wanna rework the error reporting in a more user friendly manner but that's another story.

How do i check the copied data against banned inputs when user copy & paste content?

I am developing one application that has form builder inside it to build the form. In that, i have considered special character '#' & '[]' for backend data processing against form & so i have banned user from typing the key buttons on keyboard for the respective characters too. Thing is i am done with banning user from typing so but if user copies the content from somewhere & paste into the place which supposed to contain above characters the i want to check before user pastes, the data against banned inputs. My concern is this but dont know how to do it or is it possible to do so or any other way to resolve this issue???
Thanks in advance for inputs...

Preventing the user from pressing unwanted keyes is not the best way to solve this problem. In principle you have two problem domains:
1) Preventing malicious inputs from your form to go over the wire.
The best way to do that would be to use jQuery submit() and write a validation function which a) cleans input and sends it over the wire or b) prevents submitting and shows the user an error message, not to enter malicious input.
2) You have to be concerned, that the user could bypass your form implementation and uses curl or other tools to circumvent validation on site. So, you have to take care in the backend, that the input is sanitized, before processed further.

$("textarea").bind('paste', function(e) {
var self = this;
setTimeout(function(e) {
var textval=$(self.val());
//Replace the banned keys with your custom
$("textarea").val(textval);
}, 0);
});

Try something like this:
$('#yourTextAreaId').on('paste', function (e) {
pasteContent = e.target.value;
//implement containsSpecialChars function
if(containsSpecialChars(pasteContent)){
e.preventDefault()
}
});

TypeError: Cannot read property "1" from undefined

I have some very simple code that is triggered by a google form (see http://goo.gl/lFHi3j) that asks for 2 email addresses. The code works fine when the email address is hardcoded (see commented email below) but when I try and obtain the email using e.values (when the form is submitted) is get the following error
Execution failed: TypeError: Cannot read property "1" from undefined.
(line 3, file "Code").
I've searched this forum but can't find a solution to this problem. Can anyone please help.
function onFormSubmit (e) {
// var email_address_ = "pian1966#gmail.com";
var email_address_ = e.values[1];
// Send the email
var subject_ = "Andy's Report";
var body_ = "Here is Andy's report...";
MailApp.sendEmail(email_address_, subject_, body_, {htmlBody: body_});
}

There is no e.values[1].
That is the answer to the question as to why you are getting that error.
Do a console.log(e) and familiarize yourself with what e consists of by looking at the log results in a browser debugger.
From there you can determine for yourself if e.values even exists as an array. Then go from there.

Thanks for the responses which all helped me find a solution to the problems I was having. Here's what I've discovered as I've worked on a solution:
The Google App Script must be created (as a blank script) from
responses spreadsheet and NOT out of the form itself!
In Google Forms, the developer has the option of unlinking their
responses spreadsheet and sending responses to new results
spreadsheet. If this option is selected then a new script needs to
be created from the new results spreadsheet and the code must be
copied/moved into the new script. Of course this means that a new
trigger must be created and the script needs to be authorized to
run.
Once a user submits a form, they can be given the option to
edit/correct their submission. Unless EVERY field is edited, the
script thinks the unedited fields are blank and writes "undefined"
into the resulting Google Doc. I've therefore disabled the "Edit"
option in my form to get around this.
If the user skips over irrelevant fields (leaves them blank) then
the e.values numbering order is thrown out. I have therefore made
every field compulsory with the comment that the user enter 'n/a' if a
field doesn't apply.
Having worked through these issues my form now works perfectly (albeit a little clumsily with all questions being compulsory). I would be very grateful if anyone has any suggestions on how to get around the Editing and and Blank Field problems.
(Thanks to TJ Houston for his original script)

What can I use to avoid mailto size limit?

I have read a lot of pages about avoiding the mailto length limit, but I haven't found an answer to my issue.
My problem is that I cannot send mail from the server (with PHP) because the employees have to keep a history of their emails on their private mail box.
I have to open the mail software client with some fields that are filled, after selecting one type of email.
My select looks like like this :
<select <!-- ... --> onchange="sendMailClientSide(this.value);">
<!-- ... -->
</select>
and my javascript function :
function sendMailClientSide(refType) {
// ...
var dest = "test#domain.ty";
var subj = "Why this doesn't work ?";
var body = /* a very big body */;
var linkMailto = "?bcc="+dest+"&subject="+subj+"&body="+body;
document.location.href = "mailto:"+linkMailto;
// ...
}
For some mails types, this works perfectly.
But with a body more larger than 1400 characters, the client software doesn't open.
I have tried submitting HTML form too. With this method, the limit seems to be highter but it still has a limit because it fails with a bigger mail.
And finally, I tried cutting the body (something like this "&body="+body1+"&body="+body2+...) but it doesn't work.
Anybody know if a Firefox plugin exists to expand the mailto size ? Or something like this (something from client side) ?

I don't think that it is directly possible. Maybe with a plugin, as you already suggested.
My workaround would be to provide the user with a simple form which submits to the server which then sends the mail out directly (without opening the clients mail program at all). Thus you can easily avoid the size limit at all.
The problem with this would be, that the user don't have their known email interface and thus special text formatting, custom signatures and stuff like this won't work.
You would have to decide this based on the formatting needs and who is the recipient.

Best way to obfuscate an e-mail address on a website?

I've spent the past few days working on updating my personal website. The URL of my personal website is (my first name).(my last name).com, as my last name is rather unusual, and I was lucky enough to pick up the domain name. My e-mail address is (my first name)#(my last name).com. So really, when it comes down to guessing it, it's not very hard.
Anyways, I want to integrate a mailto: link into my website, so people can contact me. And, despite my e-mail address not being very hard to guess, I'd rather not have it harvested by spam bots that just crawl websites for e-mail address patterns and add them to their database.
What is the best way for me to obfuscate my e-mail address, preferably in link form? The methods I know of are:
e-mail me
It works, but it also means that as soon as my website hits Google, I'll be wading through spam as spam bots easily pick out my e-mail address.
<img src="images/e-mail.png" />
This is less desirable, because not only will visitors be unable to click on it to send me an e-mail, but smarter spam bots will probably be able to detect the characters that the image contains.
I know that there is probably no perfect solution, but I was just wondering what everyone thought was best. I'm definitely willing to use JavaScript if necessary, as my website already makes use of tons of it.

I encode the characters as HTML entities (something like this). It doesn't require JS to be enabled and seems to have stopped most of the spam. I suppose a smart bot might still harvest it, but I haven't had any problems.

Personally, I've given up on hiding my email address. I find it easier to look into better spam-filtering solutions than worry about obfuscating. You could spend days trying to find the best way to obfuscate your address, and then all it takes is one person to sell your address to a spammer and all that work was useless.

The current accepted solution is to create a contact form that allows users to email you. If you receive a lot of spam from that (I don't on my site), then you can add a captcha for good measure, and you'll be far from the "low hanging fruit" at that point.
The fact of the matter is that if you are providing a link that a user can click on to pop open their email client with your address in the To: field, then the computer is able to decipher the email address from the page and so can a spam bot.

You mentioned this is for your personal website. On my personal site (for example, bobsomers.com) I just have a paragraph that says this:
The best way to get in contact with me
before the new site is up is to send
me an email. My email address is my
first name at this website. If you
can't figure it out from that hint,
well, you might find email more of a
challenge than figuring out my
address.
People seem to be able to figure that out just fine, as I get legitimate email all the time. Sometimes the best solutions don't require writing any code. :)

A lightweight way to obfuscate the href of an anchor is to base64-encode it:
> btoa('mailto:email#example.com')
< "bWFpbHRvOmVtYWlsQGV4YW1wbGUuY29t"
And then include it hardcoded:
E-Mail
Or dynamically server-side e.g. in PHP:
E-Mail
In combination with string reversion it could be pretty spam-save:
<?= strrev("email#example.com") ?>

Apparently using CSS to change the direction of your text works pretty well. That link has a test of a bunch of other obfuscation methods as well.
Whatever you use is inevitably going to be defeated. Your primary aim should be to avoid annoying the heck out of your users.

Don't use any obfuscation techniques here because it's probably the first place the email harvesters will look to find out how people are obfuscating emails. If you have to have your email address visible on the site don't just copy verbatim someone else's method; obfuscate it in some unique way that no other site has used so that your method won't be known to harvesters before they visit your site.

mine is actually simple:
<h3 id="email">hello#gmail.com</h3><!-- add a fake email -->
$(document).ready(function(){
//my email in reverse :)
var s = 'moc.elibomajninbew#htiek';
var e = s.split("").reverse().join("");
$('#email').html(''+e+'');
});

You could do as Google do on Google Code (and Groups). Display a par tof the email, and a clickable portion ("..."). Clicking that indicates you want to know the email, and you are asked to fill in a captcha. Afterwards the email (and others?) are visible to you.

One website I maintain uses a somewhat simplistic JavaScript means of (hopefully) keeping spambots out.
Email links call a JS function:
function sendEmail(name, domain) {
location.href = 'mailto:' + name + '#' + domain;
}
To make sure only users who have JS enabled can see the link, write them out with this:
function writeEmailLink(realName, name, domain) {
document.write('<a href="javascript:sendEmail(\''
+ name + '\', \'' + domain + '\')">');
document.write(realName);
document.write('</a>');
}
The use of one JS function to write out a link that calls another means that there are two layers of protection.

I use JavaScript obfuscation, take a look at this one for example:
http://www.jottings.com/obfuscator/

As a poster above said, I also use JavaScript obfuscation from the jottings website.
The web page generates some JavaScript which can be improved on. The mailto: text string is in the clear and identifiable by robots (which could spot this and unobfuscate this string), but if one enters into the jottings.com webpage an email address of the form mailto:addr#site.tld instead of addr#site.tld and then removes the text mailto: from the JavaScript that is generated, one suddenly has some JavaScript that does not look as though it has anything to do with email at all - just random JavaScript of which the web is full. One can improve this still further by getting rid of the link text - I replaced mine by an image of my email address that is in a fairly obscure font. Then just in case this method on jottings.com becomes popular, I randomized the variable names in the output JavaScript to make it hard for a robot to spot an instance of jottings generated JavaScript code.
Obviously some of these improvements could be built into the mechanism on jottings itself, and since the code is openly available this would be relatively easy.
An example may make this a bit more clear. I used the Jottings Obfuscator at the link above to obscure mailto:foo#bar.com (note I am cheating on the original intent of the jottings website by entering the string mailto:foo#bar.com instead of foo#bar.com) with text "Send Me Email", which jottings turned into this Javascript:
<script type="text/javascript" language="javascript">
<!--
// Email obfuscator script 2.1 by Tim Williams, University of Arizona
// Random encryption key feature by Andrew Moulden, Site Engineering Ltd
// This code is freeware provided these four comment lines remain intact
// A wizard to generate this code is at http://www.jottings.com/obfuscator/
{ coded = "3A1OTJ:rJJ#VAK.GJ3"
key = "J0K94NR2SXLupIGqVwt8EZlhznemfaPjs7QvTB6iOyWYo3rAk5FHMdxCg1cDbU"
shift=coded.length
link=""
for (i=0; i<coded.length; i++) {
if (key.indexOf(coded.charAt(i))==-1) {
ltr = coded.charAt(i)
link += (ltr)
}
else {
ltr = (key.indexOf(coded.charAt(i))-shift+key.length) % key.length
link += (key.charAt(ltr))
}
}
document.write("<a href='mailto:"+link+"'>Send Me Email</a>")
}
//-->
</script><noscript>Sorry, you need Javascript on to email me.</noscript>
After I get that back, I paste it into an editor and:
remove the mailto:
replace link text with pointer to an image of my email address
rename all the variables
replace the "noscript" section with another link to the email address image
I end up with this:
<script type="text/javascript" language="javascript">
<!--
// Email obfuscator script 2.1 by Tim Williams, University of Arizona
// Random encryption kkeoy feature by Andrew Moulden, Site Engineering Ltd
// This kudzu is freeware provided these four comment lines remain intact
// A wizard to generate this kudzu is at http://www.jottings.com/obfuscator/
{ kudzu = "3A1OTJ:rJJ#VAK.GJ3"
kkeoy = "J0K94NR2SXLupIGqVwt8EZlhznemfaPjs7QvTB6iOyWYo3rAk5FHMdxCg1cDbU"
shift=kudzu.length
klonk=""
for (variter=0; variter<kudzu.length; variter++) {
if (kkeoy.indexOf(kudzu.charAt(variter))==-1) {
lutu = kudzu.charAt(variter)
klonk += (lutu)
}
else {
lutu = (kkeoy.indexOf(kudzu.charAt(variter))-shift+kkeoy.length) % kkeoy.length
klonk += (kkeoy.charAt(lutu))
}
}
document.write("<a href='"+klonk+"'><img src='contactaddressimage.png' alt='Send Me Email' border='0' height='62' width='240'></a>")
}
//-->
</script>
<noscript>
<img src="contactaddressimage.png" border="0" height="62" width="240">
<font face="Arial" size="3"><br> </font></p>
</noscript>

I don't how well this would work. Could you not leave your email address out and make it load using an AJAX call once the page has finished loading. Not sure if spam bots can pick up the altered HTML or if they are clever enough to listen on other HTTP traffic to try and pick email addresses or if they just scan the page as it is received the first time.

One guy tested nine different ways of presenting an email address on a page and then published results on his blog.
His three best ways were:
Changing the code direction with CSS
Using CSS display:none
ROT13 Encryption
Caveat -- this was posted two years ago. Spam bots might've gotten smarter.

If you work with PHP, you can grab a free script that does that automatically. It's called "Private Daddy" and we use it for our own online audio streaming service. Just one line of code and it works out of the box... you can grab it here

Another approach could be by using a JavaScript framework and binding the data/model to the HTML elements. In the case of AngularJS, the HTML elements would be written as:
<span>{{contactEmail}}</span>
The interpolation {{data}} binding uses a scope variable that contains the actual email value. In addition, a filter could also be used that handles the decoding of the email as follows:
<span>{{contactEmail | decode}}</span>
The benefits are in the way the HTML is written. The downside is that it requires scripting support which some for may be a no no.
just another approach.

Using JQuery, but can easily be ported to plain JS if needed. Will take the following HTML block. This example I provided is also for tel: links for phone calls.
<a class="obfuscate"
href="mailto:archie...trajano...net">
archie...trajano...net
</a>
<a class="obfuscate"
href="tel:+One FourOneSix-EightFiveSix-SixSixFiveFive">
FourOneSix-EightFiveSix-SixSixFiveFive
</a>
and convert it to the proper links using Javascript.
$(".obfuscate").each(function () {
$(this).html($(this).html()
.replace("...", "#").replace(/\.\.\./g, ".")
.replace(/One/g, "1")
.replace(/Two/g, "2")
.replace(/Three/g, "3")
.replace(/Four/g, "4")
.replace(/Five/g, "5")
.replace(/Six/g, "6")
.replace(/Seven/g, "7")
.replace(/Eight/g, "8")
.replace(/Nine/g, "9")
.replace(/Zero/g, "0"))
$(this).attr("href", $(this).attr("href")
.replace("...", "#").replace(/\.\.\./g, ".")
.replace(/One/g, "1")
.replace(/Two/g, "2")
.replace(/Three/g, "3")
.replace(/Four/g, "4")
.replace(/Five/g, "5")
.replace(/Six/g, "6")
.replace(/Seven/g, "7")
.replace(/Eight/g, "8")
.replace(/Nine/g, "9")
.replace(/Zero/g, "0"))
})
I documented it in more detail here https://trajano.net/2017/01/obfuscating-mailto-links/
The de/obfuscation algorithm is pretty simple so its not too taxing to write either (no need for base64 parsing)

The Ajax call solution
The best is to have a form on the website and not to show email address, because all robots are more intelligent day after day, but if you need to show email address on the website, so, you can make it with ajax call on your server, and show it on click.
HTML
<a class="obfmail" href="#" rel="info">click here to show email address</a>
or
<a class="obfmail" href="#" rel="info">
<img src="img/click-to-show-email.jpg">
</a>
jQuery
$(document).one'click', '.obfmail', function(e) {
e.preventDefault();
a = $(this);
addr = a.attr('rel');
$.ajax({
data: {
email: addr
},
url : "/a/getemail",
type: "POST",
dataType: 'json',
success: function(data) {
a.html(data.addr);
a.attr('href', 'mailto:' + data.addr);
}
});
});
PHP
if($_POST['email']) {
...
return json_encode(array(
code => '200',
response => 'success',
addr => 'info#domain.ltd'
));
}
For more security, you can change .on by .one like this $(document).one('click', '.obfmail', function(e) { or even work with a PHP generated token that you pass into data on ajax call, to accept only one call of the ajax function like this :
html: <a class="obfmail" href="#" rel="info" token="w3487ghdr6rc">
jquery:
...
addr = a.attr('rel');
tkn = a.attr('token');
$.ajax({
data: {
email: addr,
token: tkn
}, ...
.
It is possible to encode the returned email address too or invert it.
.
Working fine for phone numbers too !

Cloudflare is now offering free email obfuscation service. This might be an option if you use Cloudlfare.

I agree with #srobinson in that using an online form for encoding to html entities seems a little shady. A few lines of python will do it for you:
def htmlEntities( string ):
return ''.join(['&#{0};'.format(ord(char)) for char in string])
htmlEntities("barnstable#example.com")
the above returns:
'barnstable#example.com'
Which is barnstable#example.com encoded to HTML Entities (surrounded by single quotes).

Honestly, your problem may be moot if you asked the question of whether or not a mailto is really what you want to use. A lot of people who use web mail, for example, or do not have the proper mail client setup in their browser are not going to benefit from a mailto. You are exposing your email address for a function that isn't going to work for a large portion of your users.
What you could do instead is use a form to send the e-mail behind the scenes so that the e-mail address is hidden and you don't have to worry about the poor saps who won't benefit from a mailto.

If you say on your site that "My e-mail address is (my first name)#(my last name).com.", and your first name and last name are pretty darn obvious, that seems to be the best spam protection you're going to get.

If anyone's using Rails, they can use the actionview-encoded_mail_to gem. (https://github.com/reed/actionview-encoded_mail_to)
There are a few options:
:encode - This key will accept the strings "javascript" or "hex".
Passing "javascript" will dynamically create and encode the mailto
link then eval it into the DOM of the page. This method will not show
the link on the page if the user has JavaScript disabled. Passing
"hex" will hex encode the email_address before outputting the mailto
link.
:replace_at - When the link name isn't provided, the
email_address is used for the link label. You can use this option to
obfuscate the email_address by substituting the # sign with the string
given as the value.
:replace_dot - When the link name isn't provided,
the email_address is used for the link label. You can use this option
to obfuscate the email_address by substituting the . in the email with
the string given as the value.

<!-- Multi-Email Obfuscator -->
<!-- step 1: # = # -->
<!-- step 2: a scrap element -->
<!-- step 3: ROT13 encode for .com -->
info<!-- step 1 -->#<!-- step 2 --><b style="display:none">my</b>domain<!-- step 3 --><script>document.write(".pbz".replace(/[a-zA-Z]/g,function(c){return String.fromCharCode((c<="Z"?90:122)>=(c=c.charCodeAt(0)+13)?c:c-26);}));</script>

Since this solution is not mentioned anywhere, but works well for me:
I do this:
create a mailto link with fake email. I like admin#localhost.localdomain for obvious reasons: Spammer might spam his own botnet when using this address unchecked.
cypher real email address and put it in an unrelated but findable hidden span or whatever element you like. Obviously to obfuscate the email and hide it from the harvester. Depending on your project structure, you might even want to put it in a JS or Session variable.
create a click handler for these links after a second that decyphers and write the correct email address into the fake mailto link not preventing defaults.
I do not think that crawlers click on mailto links, but if they would, they probaby won't wait a second, while a human being would have to be extremly fast to click a link in the first second after pageload.
Now you have a fully functional but obfuscated, honeypoted and timesecured mailto link.
Working example php file:
<html>
<head>
<title>E-Mail Obfuscating</title>
</head>
<body>
<?php
$email = "example#email.org";
echo "<a class='emailLink' href='mailto:admin#localhost.localdomain' >Send me an e-mail!</a>"
."<span style='display:none' data-hash='" . base64_encode($email) . "' />";
?>
<script>
<!--
var emailLinks = document.getElementsByClassName("emailLink");
setTimeout(function() {
for(var i=0; i <emailLinks.length; ++i){
emailLinks[i].addEventListener("click", function(){
let encodedEmail = this.nextSibling.getAttribute('data-hash');
let decodedEmail = atob(encodedEmail);
this.href = "mailto:" + decodedEmail;
this.text = decodedEmail;
});
}
}, 1000);
-->
</script>
</body>
</html>
May the code be with you.

What if creating a link "Contact me" pointing to a directory protected by a password? Of course, you have to give the pass to access.
"Contact me" > ••••••••••• > contact/index.html
Once accessed, the contact/index.html page reveals the email, a mailto for instance.

My solution is to rearrange the characters using css and replacing the element on hover. No change is visible to the user.
const obscureHoverReverseMailTo = input => `<span style="display: inline-flex; color: rgb(0, 0, 238); cursor: pointer; text-decoration: underline;" onmouseover="const newContent = [...this.children].sort((a, b) => a.style.order - b.style.order).map(el => el.innerText).join('');this.outerHTML = \`<a href='mailto: \${newContent}'>\${newContent}</a>\`">${input.split("").map((char, index) => `<span style="order: ${index}">${char}</span>`).sort(() => 0.5 - Math.random()).join("")}</span>`;
const obscureHoverReverseMailTo = input => `<span style="display: inline-flex; color: rgb(0, 0, 238); cursor: pointer; text-decoration: underline;" onmouseover="const newContent = [...this.children].sort((a, b) => a.style.order - b.style.order).map(el => el.innerText).join('');this.outerHTML = \`<a href='mailto: \${newContent}'>\${newContent}</a>\`">${input.split("").map((char, index) => `<span style="order: ${index}">${char}</span>`).sort(() => 0.5 - Math.random()).join("")}</span>`;
document.getElementById("testRoot").innerHTML = obscureHoverReverseMailTo("hello#example.com")
<div id="testRoot"></div>
<input type="text" onkeyup="document.getElementById('testOut').innerHTML = obscureHoverReverseMailTo(this.value)">
<div id="testOut"></div>
here is the function if you have something else to hide:
const obscureHoverReverse = input => `<span style="display: inline-flex" onmouseover="this.outerHTML = [...this.children].sort((a, b) => a.style.order - b.style.order).map(el => el.innerText).join('')">${input.split("").map((char, index) => `<span style="order: ${index}">${char}</span>`).sort(() => 0.5 - Math.random()).join("")}</span>`;

Simple JavaScript-unaware bots typically look for mailto: and/or # in HTML page contents. Obfuscating these keywords will dramatically decrease chances of email address scraping.
A Base-64 encoded URL template mailto:%user%#%domain% can be employed:
function contact(user, domain = location.hostname) {
const template = atob('bWFpbHRvOiV1c2VyJUAlZG9tYWluJQ==');
location.href = template
.replace('%user%', user)
.replace('%domain%', domain);
return false;
}
Where 'bWFpbHRvOiV1c2VyJUAlZG9tYWluJQ==' is btoa('mailto:%user%#%domain%').
HTML links would need to be updated as follows:
e-mail me
Furthermore, javascript: addresses can be hidden from the users:
e-mail me
The return statements prevent the page navigation to the # anchor.

I use a PHP function to generate some javascript to output the email on page load. Note that you don't need PHP to generate the JS at runtime, you can generate the JS once locally and then include the static JS in your page.
You can also use the linked function with this snippet below to automatically obfuscate email addresses in some given HTML (where $processedContent is the HTML):
$emailMatches = array();
$matchCount = preg_match_all('/(?:[a-zA-Z0-9_\.\-])+\#(?:(?:[a-zA-Z0-9\-])+\.)+(?:[a-zA-Z0-9]{2,4})+/', $processedContent, $emailMatches);
if($matchCount > 0) {
$emailMatches = $emailMatches[0];
foreach($emailMatches as $email) {
$replacement = createJSMailLink($email);
$processedContent = str_replace($email, createJSMailLink($email), $processedContent);
}