Control+backspace in textbox javascript

Question

I have a requirement of having a text-box with default value say "PF_". If I type something and press control+backspace All the values are been deleted. This problem occurs only If I have an underscore "_" at the end.

Javascript

var readOnlyLength = $('#field').val().length;
$('#output').text(readOnlyLength);
$('#field').on('keypress, keydown', function (event) {
    var $field = $(this);
    $('#output').text(event.which + '-' + this.selectionStart);
    if ((event.which != 37 && (event.which != 39)) && ((this.selectionStart < readOnlyLength) || ((this.selectionStart == readOnlyLength) && (event.which == 8)))) {
        return false;
    }
});

Html

<input id="field" type="text" value="PF_" size="50" />

I have tried a sample fiddle.

Any Idea?

Only with underscore '_' at the End deletes all the texts. Does not work with keypress keydown — Sri
– Sri, Commented Aug 14, 2015 at 7:07

user156213 · Accepted Answer · 2015-08-14 09:37:33Z

1

I'm not sure if this is what you're after, but this will reset the field to the previous value if the user tries to modify the read-only part:

$('#field').on('keypress, keydown', function (event) {
    var $field = $(this);
    var old = $field.val();
    setTimeout(function(){
        if($field.val().slice(0,3)!='PF_') {
            $field.val(old);
        }
    },0);
});

Edit: in response to op's comments, try this code instead:

$('#field').on('keypress, keydown', function (event) {
    var $field = $(this);
    if(event.ctrlKey && event.which==8) { // ctrl-backspace
        $field.val('PF_');
        return false;
    }
    var old = $field.val();
    setTimeout(function(){
        if($field.val().slice(0,3)!='PF_') {
            $field.val(old);
        }
    },0);
});

Fiddle

edited Aug 14, 2015 at 9:37

answered Aug 14, 2015 at 7:25

user156213

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2 Comments

Sri Over a year ago

Nice one. But This is not I was looking for. I dont want the previous value when control+bkspce. The values should be deleted.

user156213 Over a year ago

Edited my answer; is the new fiddle what you want?: jsfiddle.net/2hx7dak0/18

Ahs N · Accepted Answer · 2015-08-14 07:22:35Z

0

This is how I would do it:

$("#field").keyup(function(e){
    if($(this).val().length < 3){
        $(this).val("PF_");
    }
});

Here is the JSFiddle demo

answered Aug 14, 2015 at 7:22

Ahs N

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