"Error in use of Bolean type of Javascript."

arbab · February 23rd, 2011, 02:07 AM

"Error in use of Bolean type of Javascript."
Syntax error is coming in document.write(true*5+false*7=) in the following program:
1-<html><head><title>Conversion between types, Quotes, Formatting characters</title>
2-<body>
3-<script language="Javascript">
4-document.write("true*5+false*7=")
5-document.write(true*5+false*7=)
6-</script>
7-</body></html>
Whatâs wrong in the 5th line document.write(true*5+false*7=) of this program?
Thanks in advance.

joefawcett · February 23rd, 2011, 04:30 AM

It's because you have an = sign at the end, remove that and it should be fine.

(Please do not include Google Analytics tracking script in questions on the forum unless your question relates directly to that.)

arbab · February 23rd, 2011, 05:06 AM

Yea it worked, but I did not understand the reason that why after excluding =, it worked fine, could you please explain.

Imar · February 23rd, 2011, 06:57 AM

Quote:

(Please do not include Google Analytics tracking script in questions on the forum unless your question relates directly to that.)

That is actually a bug in the e-mail notificaton for this forum. Ran into that a couple of times as well. It seems that the code that sends the notifications adds it to messages that contain something like </body>. So you only see this in the e-mail, not the actual post....

Imar

joefawcett · February 23rd, 2011, 09:18 AM

Thanks Imar and apologies to arbab, thanks for that. I wondered why I kept seeing it...

joefawcett · February 23rd, 2011, 09:23 AM

Because document.write is trying to evaluate the expression you give it.

Code:

(true*5+false*7=)

is not a vaild expression because it cannot be evaluated, you have an equals sign indicating an equation but nothing after it, what does it mean?

Code:

(true*5+false*7)

is a valid expression that evaluates to 5 as true converts to 1, false to 0 and multiplication has a higher priority than addition giving (1 * 5) + (0 * 7).

arbab · February 25th, 2011, 01:57 AM

Yea such impressions document.write(1*15+0*7) multiplying the digits, thanks for your guidance.