Keypress and regex validation
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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 '18 at 17:59
Jon KJon K
608
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 '18 at 17:59
Jon KJon K
608
"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 '18 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 '18 at 17:59
Jon KJon K
608
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 '18 at 17:59
Jon KJon K
608
asked Nov 22 '18 at 17:59
Jon KJon K
608
asked Nov 22 '18 at 17:59
Jon KJon K
608
asked Nov 22 '18 at 17:59
Jon KJon K
608
asked Nov 22 '18 at 17:59
Jon KJon K
608
608
"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 '18 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 '18 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 '18 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 '18 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 '18 at 18:17