Javascript TRUE is not defined or in quotes

Question

I have a XML file that contains

<car>
    <id>123</id>
    <sunroof>FALSE</sunroof>
    <service>TRUE</service>
</car>

The following code only works if I wrap TRUE inside quotes e.g (service == "TRUE")

var service = tis.find("service").text();

if(service === TRUE){
    var service_tag = '<a title="Service" href="">Service</a>'
} else {
    var service_tag = '';
}

Boolean true is different from string `"TRUE"`, works as designed — Pekka, Oct 04 '11 at 16:17

score 29 · Accepted Answer · answered Oct 04 '11 at 16:18

Without quotes javascript will try to interpret TRUE as a value / expression. There is no value TRUE natively defined in javascript. There is true but javascript is case sensitive so it won't bind TRUE to true.

The value you get back from text() is a string primitive. Writing "TRUE" gives you back the string "TRUE" which does compare succesfully with the value service

score 9 · Answer 2 · answered Oct 04 '11 at 16:18

9

JavaScript boolean true and false are lower case.

answered Oct 04 '11 at 16:18

MeLight

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WEFX · Answer 3 · 2012-09-12T18:44:49.417

3

Set service equal to this, so JavaScript will be able to interpret your values:

var service = tis.find("service").text().toLowerCase();

edited Sep 12 '12 at 18:44

answered Sep 12 '12 at 15:14

WEFX

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score 1 · Answer 4 · answered Jul 06 '21 at 08:50

1

I had this error because I quickly typed it with typo

someBooleanVar === ture

this is wrong

it should be true not ture

answered Jul 06 '21 at 08:50

Basheer AL-MOMANI

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score 1 · Answer 5 · edited May 23 '17 at 10:30

1

its because the tripe equal also check for type, and TRUE it's a identifier "TRUE" is a value

// this will work
if(service === "TRUE"){
    var service_tag = '<a title="Service" href="">Service</a>'
} else {
    var service_tag = '';
}

Difference between == and === in JavaScript

edited May 23 '17 at 10:30

Community

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answered Oct 04 '11 at 16:17

Roberto Alarcon

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2

ha, this is not what he/she was asking, the real issue was miss spelling, its `true` not `True` – Ace Mar 30 '20 at 09:31

score 1 · Answer 6 · answered Oct 04 '11 at 16:18

1

This is expected.

tis.find("service").text(); returns a string, not a boolean, and the JavaScript boolean for truth is true (which is case sensitive, like everything else in the language).

answered Oct 04 '11 at 16:18

Quentin

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score 1 · Answer 7 · answered Oct 04 '11 at 16:21

1

var service = tis.find("service").text();

This returns a string "TRUE". Since === checks for the type as well, it always returns false.

answered Oct 04 '11 at 16:21

Sajith Nair

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2

score 1 · Answer 8 · answered Oct 04 '11 at 16:23

1

TRUE refers to a variable named TRUE which doesn't exist, so you get an error. "TRUE" is a string containing the characters TRUE. Your variable service will contain a string, so the second of these are what you want.

answered Oct 04 '11 at 16:23

Andrew Wilkinson

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Javascript TRUE is not defined or in quotes

8 Answers8