Today #day23 of #100daysofcode, I have completed 3 lessons and a practice program in JS, thus making the First module 1 complete in JS course. @Sololearn

1. Comments in JS

what is a comment in JavaScript and why we need?

• A comment is a non-executable JavaScript instruction.
• Comments help you are code more readable.

how to write a comment for single line?

• Add Two forward slash// to your code line.

how to write comment for multiple lines or JS block?

• Add /* at beginning of line and add */ at end of the line.

2. Data Types

i. what are the data types?

• data types of different types of values a program language can take input.
• JavaScript can handle many different types of data like numbers, strings, arrays.

  Note:

  • In JavaScript you can redeclare the same variable name with another data type value.
  • Var isn't correct keyword. var is correct keyword in JS. Js is case sensitive.

ii. String Data Type

• String data type in JavaScript stores string data value.
• you can store manipulate text in string data type.
• If you start a string with single quote then you need to end with single quote. -\ is an escape character. Example:

var name1 = "My name is Dheeraj"
document.write(name1) \\My name is Dheeraj

var name1="<br>I am 'batman'"
document.write(name1) \\I am 'batman'

var name1="<br>I am \'Ironman\'"
document.write(name1) \\I am 'Ironman'

Code: output

iii. Boolean datatype

• boolean data type returns true or false.
• the boolean value of zero null undefined empty string is false.
• the boolean value of real value is true.

Image

Conclusion

• Comments in javascript.
• Data types in JavaScript.
• String data types
• Boolean data types
• Program problems
• Quiz

References Sololearn

Author: Dheeraj.y

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