JavaScript Best Practices, Exercises of Javascript programming

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JAVASCRIPT

BEST

PRACTICES.

@Ezenagu Emmanuel JS TIPS BY EMMANUEL

Following JavaScript best practises can aid in faster

page loads and improved performance, as well as

improved code readability and ease of

maintenance and debugging. Carefully written

code can also help to avoid errors and security

issues.

Always Declare Local Variables

• Local variables should be declared for all variables used in a function.
• If the var, let, or const keyword is not used when declaring a local variable, the local variable will be converted to a global variable.

Declarations on Top All declarations should be placed at the beginning of each script or function as good coding practise. This will result in:

• A cleaner code
• Give users a single location to look for local variables.
• Make it simpler to avoid undesirable (implied) global variables.
• Reduce the likelihood of unwanted re-declarations.

Initialize Variables When you declare variables, you should always initialise them. This will:

• Provide cleaner code
• Provide a single location for variable initialization.
• Avoid using undefined values.

Declare Arrays with const

• Declaring arrays with const prevents

accidental type changes:

Don't Use new Object()

• Instead of new String(), use "".
• Instead of new Number(), use 0
• Instead of using new Boolean(), use false
• Rather than new Object(), use {}
• Instead of using new Array(), use [].
• Instead of using new RegExp(), use /()/.
• Instead of using new Function(), use function (){}.

Example;

Example;

Use === Comparison

• Prior to comparison, the == comparison operator

converts (to types that match).

• The === operator requires a value and type

comparison:

Use Parameter Defaults

• When a function is called with an unspecified

argument, the value of the unspecified argument is

set to undefined.

• Undefined values can cause your code to fail.

Assigning default values to arguments is a good

practise.

Example;

Example;

Avoid Number, String, and Boolean as Objects

• Numbers, strings, and booleans should always be

treated as primitive values, not as objects.

• Declaring these types as objects slows execution

and has negative side effects: