Keypress and regex validation
I've recently come across the following code which tests an input value against a regex.
It's written with jQuery and listens for 'keypress' changes.
$('form').each(function (i, elem) {
$(elem).on('keypress', '.my-input-field', function (event) {
var theEvent = event || window.event;
var key = theEvent.keyCode || theEvent.which;
key = String.fromCharCode(key);
var regex = /[0-9]|.|t/;
if (!regex.test(key) && !theEvent.shiftKey) {
return false;
}
});
}
I'm interested to know why you might want to listen for a 'keypress' (rather than say 'input' or 'change') and i'm also a bit confused about the code that checks for 'window.event' and 'theEvent.which' and why they are needed rather that only the 'event' object.
I feel that the code could be simplified (with JS) as follows -
document.addEventListener('change', function(e) {
var regex = /[0-9]|.|t/;
if(e.target.classList.contains('my-input-field') {
if (!regex.test(e.target.value)) {
return false;
}
})
});
Alternatively, and possibly even more straightforward, since no validation error is actually displayed why not just use a number field to prevent anything non numeric characters from being entered.
<input type="number" class="my-input-field">
Just curious to see if I've missed something fundamental in my understanding of what the original code is doing. Any help much appreciated.
Thanks,
J.
javascript javascript-events keypress
asked Nov 22 at 17:59
Jon K
556
add a comment |
I've recently come across the following code which tests an input value against a regex.
It's written with jQuery and listens for 'keypress' changes.
$('form').each(function (i, elem) {
$(elem).on('keypress', '.my-input-field', function (event) {
var theEvent = event || window.event;
var key = theEvent.keyCode || theEvent.which;
key = String.fromCharCode(key);
var regex = /[0-9]|.|t/;
if (!regex.test(key) && !theEvent.shiftKey) {
return false;
}
});
}
I'm interested to know why you might want to listen for a 'keypress' (rather than say 'input' or 'change') and i'm also a bit confused about the code that checks for 'window.event' and 'theEvent.which' and why they are needed rather that only the 'event' object.
I feel that the code could be simplified (with JS) as follows -
document.addEventListener('change', function(e) {
var regex = /[0-9]|.|t/;
if(e.target.classList.contains('my-input-field') {
if (!regex.test(e.target.value)) {
return false;
}
})
});
Alternatively, and possibly even more straightforward, since no validation error is actually displayed why not just use a number field to prevent anything non numeric characters from being entered.
<input type="number" class="my-input-field">
Just curious to see if I've missed something fundamental in my understanding of what the original code is doing. Any help much appreciated.
Thanks,
J.
javascript javascript-events keypress
asked Nov 22 at 17:59
Jon K
556
"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but thenumbertype is only available since HTML 5.1 and only works in IE since v10.
– Andreas
Nov 22 at 18:17
add a comment |
I've recently come across the following code which tests an input value against a regex.
It's written with jQuery and listens for 'keypress' changes.
$('form').each(function (i, elem) {
$(elem).on('keypress', '.my-input-field', function (event) {
var theEvent = event || window.event;
var key = theEvent.keyCode || theEvent.which;
key = String.fromCharCode(key);
var regex = /[0-9]|.|t/;
if (!regex.test(key) && !theEvent.shiftKey) {
return false;
}
});
}
I'm interested to know why you might want to listen for a 'keypress' (rather than say 'input' or 'change') and i'm also a bit confused about the code that checks for 'window.event' and 'theEvent.which' and why they are needed rather that only the 'event' object.
I feel that the code could be simplified (with JS) as follows -
document.addEventListener('change', function(e) {
var regex = /[0-9]|.|t/;
if(e.target.classList.contains('my-input-field') {
if (!regex.test(e.target.value)) {
return false;
}
})
});
Alternatively, and possibly even more straightforward, since no validation error is actually displayed why not just use a number field to prevent anything non numeric characters from being entered.
<input type="number" class="my-input-field">
Just curious to see if I've missed something fundamental in my understanding of what the original code is doing. Any help much appreciated.
Thanks,
J.
javascript javascript-events keypress
asked Nov 22 at 17:59
Jon K
556
I've recently come across the following code which tests an input value against a regex.
It's written with jQuery and listens for 'keypress' changes.
$('form').each(function (i, elem) {
$(elem).on('keypress', '.my-input-field', function (event) {
var theEvent = event || window.event;
var key = theEvent.keyCode || theEvent.which;
key = String.fromCharCode(key);
var regex = /[0-9]|.|t/;
if (!regex.test(key) && !theEvent.shiftKey) {
return false;
}
});
}
I'm interested to know why you might want to listen for a 'keypress' (rather than say 'input' or 'change') and i'm also a bit confused about the code that checks for 'window.event' and 'theEvent.which' and why they are needed rather that only the 'event' object.
I feel that the code could be simplified (with JS) as follows -
document.addEventListener('change', function(e) {
var regex = /[0-9]|.|t/;
if(e.target.classList.contains('my-input-field') {
if (!regex.test(e.target.value)) {
return false;
}
})
});
Alternatively, and possibly even more straightforward, since no validation error is actually displayed why not just use a number field to prevent anything non numeric characters from being entered.
<input type="number" class="my-input-field">
Just curious to see if I've missed something fundamental in my understanding of what the original code is doing. Any help much appreciated.
Thanks,
J.
javascript javascript-events keypress
javascript javascript-events keypress
asked Nov 22 at 17:59
Jon K
556
asked Nov 22 at 17:59
Jon K
556
asked Nov 22 at 17:59
Jon K
556
asked Nov 22 at 17:59
Jon K
556
asked Nov 22 at 17:59
Jon K
556
556
"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but thenumbertype is only available since HTML 5.1 and only works in IE since v10.
– Andreas
Nov 22 at 18:17
add a comment |
"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but thenumbertype is only available since HTML 5.1 and only works in IE since v10.
– Andreas
Nov 22 at 18:17
"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but the
number type is only available since HTML 5.1 and only works in IE since v10.– Andreas
Nov 22 at 18:17
"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but the
number type is only available since HTML 5.1 and only works in IE since v10.– Andreas
Nov 22 at 18:17
add a comment |
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"I feel that the code could be simplified (with JS) as follows" - Don't feel it but test it. Do the scripts really react the same way? "why not just use a number field" - That would now be the way to go, but the
numbertype is only available since HTML 5.1 and only works in IE since v10.– Andreas
Nov 22 at 18:17