Friday, 10 March 2017

Javascript Debugging & Mathematical Operators



Hello Buddies,


Here are 2 javascript encounters, few more are about to come.



1. While working with JSP and JS, a person habitual of using debug mode in Eclipse, might feel that something is missing, in understanding the UI flow.


For such incidents, one can always use either of the ways to confirm what values are being set or how the flow is being considered.

Common UI debugging techniques -


1. console.log() - to print variables’ values in javascripts, without impacting the UI.

2. F12 debugs – it gives you power to put breakpoints in the scripts listed in ‘sources’ window, check the requests and responses of various APIs invoked, time taken for the calls made, as well as make minor changes in the style section, or other HTML components.

3. document.write()it writes any value you want to display on the UI, without any format.

4. alert() - it shows the immediate values of javascripts’ variables, and this method is often used by developers to make sure if the desired javascript is invoked.




2. Secondly, while having the hands on with some javascript basics, encountered a behavior which I felt might come handy in evaluating javascript skills.


Quoted literals (either single or double quotes), in a mathematical expression, will make the entire line as a string, somewhat like concatenation, as far as I could understand.


Following are some observations -

2 + 3 * 5 = 17
'2' + 3 * 5 = 215
'2' + '3' * 5 = 215
'2' + '3' * '5' = 215
'2' + '3' - '5' = 18
'2' + '3' / '5' = 20.6


So beware of such scenarios if asked. What we observed here is that though the literals are being regarded as string, but that holds true only or ‘+’ operator. For any other mathematical operator, literals are still regarded as numbers, and the results will be accordingly. Please have a thorough look at the above results.


Feel free to put your inputs.

Happy coding.

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