Convert data. The value of the data atype variable.

# Web Site Writing Basics

# javascrip

# data atype

Type Conversion or Type Casting in JavaScript can be done in a variety of ways depending on which type you want to convert the data to. This is essentially a back-and-forth conversion between String, Number and Boolean.

Here are some of the main ways to convert data types:

1.Converting to String (text)

You can convert any data into String using three main ways:

Method Code Sample Results

String (value) (function) String (123) "123"

String (true) "true"

value.toString () (method) (123) .toString () "123"

(false) .toString () "false."

String Concatenation (The Easiest Way) 123 + "" 123 "

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2. Conversion to Number (number)

Converting data into numbers is the most common and sensitive:

Method Code Sample Results Remembering

Number (value) (function) Number ("123") 123 changes null to 0, true to 1, false to 0, and non-number text (such as "hello") to NaN (Not a Number).

Unary Plus (+) + "123" 123 is a short and fast way to convert to numbers.

+ true 1

ParseInt (string) parseInt ("100px") 100 converts to an integer (Integer), stopping when it comes across a non-numeric character.

ParseFloat (string) parseFloat ("10.5em") 10.5 Converted to decimal (floating-point)

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Number () examples to watch out for:

JavaScript

Number ("123"); / / 123

Number ("12 34"); / / NaN (with space between numbers)

Number ("abc"); / / NaN

Number (null); / / 0

Number (undefined); / / NaN

3. Conversion to Boolean (true / false)

You can convert any data into a Boolean using two main ways:

Method Code Sample Results

Boolean (value) (function) Boolean (1) true

Boolean (0) false

Double NOT (!!)!! 1 true

!! 0 false

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The following values are converted to false (called Falsy Values):

Value (Value) Data Type

0 Number

"" (String empty) String

Null Object

Undefined Undefined

NaN Number

False Boolean

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All other values are converted to true (called Truthy Values), such as "0," "[] (Array is empty), or {} (Object is empty).

💡 Type Coercion (implicit data type conversion)

JavaScript also provides Implicit Conversion, also known as Type Coercion, when some Operators are in use, such as:

Operator + (addition): If one of the values is String, convert the other into String and connect String instead of adding numbers.

JavaScript

"10" + 5; / / "105" (5 was converted to "5")

10 + "5"; / / "105" (10 was converted to "10")

Other mathematical Operators (-, *, /): will try to convert all values into Numbers.

JavaScript

"10" - 5; / / 5 ("10" is converted to 10)

"10" * "2"; / / 20 ("10" and "2" were converted to 10 and 2)

Operator in terms (= =): Will convert the data type to the same before comparing.

JavaScript

"5" = = 5; / / true (5 is converted to "5" before comparison)

Instructions: To keep the code clear and prevent errors, Explicit Conversion (Explicit Conversion, such as Use Number () or String ()) should be used, and use Strict Equality Operator (= = =) to compare values and data types directly without implicit data conversion.