JS Comments

JavaScript Comments

Ø  The comments are a meaningful way to express the structure and function of the code. It is used to add information about the code structures.

Ø  As the complexity of your scripts grows, comments help you (and others) understand their structure when you come to view the code at a later date.

Ø  A lot of code created quickly is said to be “write-only” code, as it suffers from an inherent lack of structure or commenting.

Ø  Debugging such code, or reusing it months later, becomes maddeningly impossible as you try to remember what a certain line was supposed to do, or why using certain values seems to stop your code from working.

Ø  Comments are completely ignored by JavaScript and have no effect on the speed at which your scripts run, provided they are properly formed.

Ø  Comments can slow the loading of your page, however – many coders keep a “development” copy of their code fully commented for editing, and remove all comments from their code when they finally publish it.

Ø  There are two types of comments in JavaScript – single-line comments, and multi-line comments.

1)    Single-line comments

Ø  Single-line comments begin with two forward-slash characters (//) and end with a new line. It can be used before and after the statement.

// this is single line comment

console.log("hello"); // this is single line comment


2)   Multi-line Comments

Ø  You can add multiple-line comments by enclosing the comment block between /* and */.


/* comments are ignored by JavaScript. */

console.log("Hello World");


/* a one-line, “multi-line” comment */



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