Day29 JS notes 2021.09.23

Math Built-in objects ：

- Math.PI PI

- Math.abs() The absolute value

- Math.max() Maximum

- Math.min() minimum value

- Math.ceil() Rounding up ( Ceiling function )

- Math.floor() Rounding down ( Floor functions )

- Math.round() rounding

- Math.random() random number （0~1）

If the element in the built-in object is a string ：

- When the content of a string is a number Converts to numeric type by default

- When the content of the string is Chinese characters Returns the NaN(not a number)

Date object ：Date function   （GMT Standard time Greenwich / GMT 1970-1-1 00:00:00）

How it was created :new Date()

Acquisition time ：

  expand ： Display the output results in the browser ：    structure .innerHTML = Output results

Setup time ：

Time stamp ： Converts the current time to milliseconds

1）  Date object  . getTime()

2） In the... Of the creation date object new Add one in front +

Formatting settings for dates ：

1. Convert to date toLocaleDateString()

2. Convert to hours, minutes and seconds toLocaleTimeString()

3. Convert to month, day, hour, minute and second toLocaleString()

Conversion between bases ：

tostring Method to convert a decimal number to another base

 parseInt Method to convert other base digits to decimal （ The second parameter value defaults to 10 Base number ）