20241128_1 Type Conversion

new Set() Method

• Passing an array to new Set()
• Create an empty set and use add() to add values
• if a specified value exists in a set. use has()
• .values(), . forEach (function), .keys(), .entries()
• ex) const letters = new Set(["a","b","c"]); 

new Map() Method

 a map by passing an array to the new Map() constructor

• value of a key in a map with the get() method
• elements to a map with the set() method(ex) fruits.set("apples", 500); )
• .size(), .delete(key), .clear(), .has(key), .entries(), foreach(), . keys(), .values(), 
• ex) const fruits = new Map([["apples", 500],  ["bananas", 300],  ["oranges", 200]]);

Converting Strings to Numbers

 

Number()	Returns a number, converted from its argument
parseFloat()	Parses a string and returns a floating point number
parseInt()	Parses a string and returns an integer

Converting Numbers to Strings

 

toExponential()	Returns a string, with a number rounded and written using exponential notation.
toFixed()	Returns a string, with a number rounded and written with a specified number of decimals.
toPrecision()	Returns a string, with a number written with a specified length

 

Converting Dates to Strings

MethodDescription

getDate()	Get the day as a number (1-31)
getDay()	Get the weekday a number (0-6)
getFullYear()	Get the four digit year (yyyy)
getHours()	Get the hour (0-23)
getMilliseconds()	Get the milliseconds (0-999)
getMinutes()	Get the minutes (0-59)
getMonth()	Get the month (0-11)
getSeconds()	Get the seconds (0-59)
getTime()	Get the time (milliseconds since January 1, 1970)