You can place whitespace after slashes, this vector finds out what entities you can place after them.
const div = document.createElement('div')div.innerHTML='<a href="//$[data1]example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
log('$[data1]');0x0D
}div.innerHTML='<a href="//\example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('\');0x0D
}div.innerHTML='<a href="//@example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('@');0x0D
}div.innerHTML='<a href="//​example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('​');0x0D
}div.innerHTML='<a href="//​example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('​');0x0D
}div.innerHTML='<a href="//​example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('​');0x0D
}div.innerHTML='<a href="//​example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('​');0x0D
}div.innerHTML='<a href="//
example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('
');0x0D
}div.innerHTML='<a href="//⁠example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('⁠');0x0D
}div.innerHTML='<a href="//­example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('­');0x0D
}div.innerHTML='<a href="///example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('/');0x0D
}div.innerHTML='<a href="//	example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('	');0x0D
}div.innerHTML='<a href="//​example.com">';0x0D
if(div.querySelector('a').host === 'example.com') {0x0D
alert('​');0x0D
}