Javascript null or empty control does not work

Question

I open this subject for second time.

However there is no solution.

Below code does not work. I can enter empty(Space) value.

var veri = {
YeniMusteriEkleTextBox: $('#YeniMusteriAdiTextbox_I').val(),
};
if (!veri.YeniMusteriEkleTextBox) {
alert("Customer name can not be empty!");
}

@mplungjan it's not strictly identical - the answers to the other question (from which this code came) failed to mention the need to `trim` the input to remove leading and trailing whitespace — Alnitak, Sep 13 '13 at 06:42
Regardless, the correct approach is clearly to edit the other question. There is no interaction from the OP on the other question at all. — Chris Hayes, Sep 13 '13 at 06:43

Alnitak · Answer 1 · 2013-09-13T07:37:52.980

2

You need to .trim the value to remove leading and trailing white space:

var veri = {
    YeniMusteriEkleTextBox: $('#YeniMusteriAdiTextbox_I').val().trim()
};

The .trim method doesn't exist on some older browsers, there's a shim to add it at the above MDN link. Since you're using jQuery you could also use $.trim.

edited Sep 13 '13 at 07:37

answered Sep 13 '13 at 06:43

Alnitak

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So answer the other question and leave this one to rot - and use $.trim() to not have to use the shim – mplungjan Sep 13 '13 at 06:43
@mplungjan in general I recommend using shims instead of adhoc library replacements for "standard" ES5 functions so as to encourage use of those standard APIs as and when they're supported "out of the box" by newer browsers. – Alnitak Sep 13 '13 at 08:00
If you already use jQuery there is absolutely no need to add a shim in my opinion. jQuery already uses .trim if available and a shim if not – mplungjan Sep 13 '13 at 08:13

Alex · Answer 2 · 2013-09-13T06:58:33.270

1

You need to remove all the whitespaces to achieve that

var veri = {
    YeniMusteriEkleTextBox: $('#YeniMusteriAdiTextbox_I').val().replace(/^\s+|\s+$/g, '')
};
if (!veri.YeniMusteriEkleTextBox) {
    alert("Customer name can not be empty!");
}

UPD: Some additional information

Your object

var veri = {
    YeniMusteriEkleTextBox: $('#YeniMusteriAdiTextbox_I').val(),
};

has a comma after last key-value pair. This can cause an error in IE.

Right ways is:

var obj = {
    key1: 'val1',
    key2: 'val2' // no comma after last pair
}

edited Sep 13 '13 at 06:58

answered Sep 13 '13 at 06:43

Alex

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and what it whitespace _within_ the string is legal? – Alnitak Sep 13 '13 at 06:47
@Alnitak String.prototype.trim=function(){return this.replace(/^\s+|\s+$/g, '');}; Same regex :) although You are right, it might be useful to add the .trim() method – Alex Sep 13 '13 at 06:53
Which jQuery does for free. $.trim() – mplungjan Sep 13 '13 at 07:08
When I wrote that comment it wasn't the same regex - you had `/\s/g` – Alnitak Sep 13 '13 at 07:35
@Alnitak yes I've changed that without mentioning, I'm sorry – Alex Sep 13 '13 at 07:40

score 0 · Answer 3 · answered Sep 13 '13 at 06:42

0

Have you tried:

if (veri.YeniMusteriEkleTextBox!='') {
alert("Customer name can not be empty!");
}

answered Sep 13 '13 at 06:42

eggshot

190
6

That would be very silly unlesss you meant to use it as a debug to see if the statement was executed at all – mplungjan Sep 13 '13 at 07:09

score 0 · Accepted Answer · answered Sep 13 '13 at 06:42

0

Try this

var veri = {
YeniMusteriEkleTextBox: $('#YeniMusteriAdiTextbox_I').val(),
};
if (veri.YeniMusteriEkleTextBox.trim()=="" || veri.YeniMusteriEkleTextBox==undefined) {
alert("Customer name can not be empty!");
}

answered Sep 13 '13 at 06:42

Amit

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Thank you so much Amit , your code works! – user2706372 Sep 13 '13 at 06:46

Javascript null or empty control does not work

4 Answers4