js data type conversion example

This article mainly shares with you JS data type conversion examples, hoping to help everyone.

Basic data types

Convert other data types to number type

• ##isNaN, Number, parseInt, parseFloat

• When performing mathematical operations of addition, subtraction, multiplication and division

true -> 1  false -> 0'' ->
 0'1' -> 1'12px' -> true/12/NaNnull ->
  0undefined -> NaN{} /^$/ function()
  {} -> NaN[] -> 0[12,23] -> NaN//=>
   通过toStirng把数组转换为字符串<br>
   // 然后Number把字符串转换为数字

Mathematical operations in js

• +, -, *, / Addition, subtraction, multiplication and division

• Except for the addition operation, which has special features, the rest of the operators are mathematical operations, that is, when encountering Non-numeric types, first convert to

  number type, and then calculate
  

1-'1' -> 010 * null -> 010 / undefined -> NaN10 * [10] -> 100

• Speciality of addition: When encountering a string, + is String concatenation is a mathematical operation without encountering a string

1+'1' -> '11'null+'1' -> 'null1'//=>把其他值先转换为字符串再进行拼接对象.toString() -> '[object object]'

Thinking

1+null+true+undefined+[]+'xieth'+null+undefined+[]+10

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Result

"NaNxiethnullundefined10"Number(undefined) -> 
NaN//Number在进行转换的时候，只要包含非有效数字，返回都为NaN

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Convert other types to Boolean types

• Boolean,!,!!

• When judging conditions , also converted to Boolean type, and then verify the true or false condition

Only 0 NaN null undefined empty string-> Convert to false

The rest are true

Convert other data types to number type

• isNaN, Number, parseInt, parseFloat

• When performing mathematical operations of addition, subtraction, multiplication and division

true -> 1  false -> 0'' -> 0'1' -> 1'12px' -> 
true/12/NaNnull -> 0undefined -> NaN{} 
/^$/ function(){} -> NaN[] -> 0[12,23] -> 
NaN//=> 通过toStirng把数组转换为字符串<br>
// 然后Number把字符串转换为数字

Mathematical operations in js

• +, -, *, / Addition, subtraction, multiplication and division

• In addition to addition operations, there are special features , the rest of the operators are all mathematical operations, that is, when encountering a non-numeric type, first convert it to the

  number type, and then perform the calculation
  

1-'1' -> 010 * null -> 010 / undefined -> NaN10 * [10] -> 100

• addition The particularity: when encountering a string, + is string concatenation, and when not encountering a string, it is a mathematical operation

1+'1' -> '11'null+'1' -> 'null1'//=>把其他值先转换为字符串再进行拼接对象.toString() -> '[object object]'

Thinking

1+null+true+undefined+[]+'xieth'+null+undefined+[]+10

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Copy after login

Result

"NaNxiethnullundefined10"Number(undefined) -> NaN//Number在进行转换的时候，只要包含非有效数字，返回都为NaN

Copy after login

Convert other types to Boolean types

• Boolean,!,!!

• When judging the condition, it is also converted to Boolean type, and then the true or false condition is verified.

Only 0 NaN null undefined empty string -> Convert to false

The rest are true

JavaScript Basics Data Type

Detailed explanation of php constants and data type instances

Detailed explanation of special data types in JavaScript

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