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JavaScript Coding Guidelines | PPTX
JAVASCRIPT
CODING GUIDELINES
_by Oleksii Prohonnyi
BEST
PRACTICES
Use === Instead of ==
"If two operands are of the same
type and value, then === produces
true and !== produces false.“
- JavaScript: The Good Parts
Eval = Bad
Not only will this decrease your script's
performance substantially, but it also
poses a huge security risk.
Don't Use Short-Hand
This is a terrible practice that should be
avoided at all costs.
Declarations on Top
It is a good coding practice to put all
declarations at the top of each script
or function.
Initialize Variables
It is a good coding practice to initialize
variables when you declare them.
Use shortcut declarations
- Use {} instead of new Object()
- Use "" instead of new String()
- Use 0 instead of new Number()
- Use false instead of new Boolean()
- Use [] instead of new Array()
- Use /()/ instead of new RegExp()
- Use function (){} instead of new function()
Avoid Global Variables
Minimize the use of global variables.
This includes all data types, objects,
and functions.
Global variables and functions can be
overwritten by other scripts.
Use local variables instead, and learn
how to use closures.
Always Declare Local Variables
All variables used in a function should
be declared as local variables.
Local variables must be declared with
the “var” keyword, otherwise they will
become global variables.
Long List of Variables?
Omit the "Var" Keyword and
Use Commas Instead
Say “No!” to loops declarations
Do not declare variables inside loops,
don't make the engine work any harder
than it must.
End Your Switches with Defaults
Always end your switch statements
with a default. Even if you think there
is no need for it.
Avoid Cluttering The Global
Namespace
Using globals may cause naming conflicts
between javascript source files and cause
code to break. For this reason, it is a good
practice to encapsulate functionality within
a single global namespace.
Avoid sync "Ajax" calls
If you think that your situation requires
sync mode, it is most likely time to
re-think your design. Very few (if any)
situations actually require Ajax requests
in sync mode.
Use JSON
When storing data structures as plain
text or sending/retrieving data structures
via Ajax, use JSON instead of XML
when possible.
Comment Your Code
Always comment important sections
of your code.
JAVASCRIPT
OOD
Object
Objects can be created using a constructor
or an object literal.
The constructor should be a custom function
only.
Constructor
Constructor functions simply assign values
to slots of a newly created object.
Inheritance
JavaScript supports inheritance hierarchies
through prototyping in the manner of Self.
Encapsulation
Encapsulation includes the idea that the
data of an object should not be directly
exposed.
CODE
CONVENTION
Always follow team’s code convention!
REFERENCES
1. “Clean Code: A Handbook of Agile Software
Craftsmanship” (Robert Martin)
2. “Even Faster Web Sites” (Steve Souders)
3. “Maintainable JavaScript” (Nicholas Zakas)
4. w3schools.com
5. javascripttoolbox.com
6. tutsplus.com
SIGMA UKRAINE38
Oleksii Prohonnyi
facebook.com/oprohonnyi
linkedin.com/in/oprohonnyi

JavaScript Coding Guidelines