Primitive Data Types-基礎篇(14)

六種 JS 基本類型

可參考第一篇 JavaScript-基本型別(1) 觀看

基本六種型別

1. Nunber
2. String
3. Boolean
4. Undefined
5. Null
6. Symbol

1. Number

(1) toString(變為字串)

e.g.
let age = 27;
console.log(age.toString() +10);
//** 結果就會變為字串 就會變為 2710 **//

(2)toFixed (取得某位數)

e.g.
let pi = 3.1415926535;
console.log(pi.toFixed(2));
/*** 就會得出 3.14 ***/

2. String

(1)property(length長度)

let name= "ken";
console.log(name.length);

(2)index(索引)

從零開始計算

let name= "ken";
console.log(name[1]); //e

(3)slice(切片)

let name= "ken is good";
console.log(name.slice(1, 3)); //en

(4)indexOf (查詢index number)

let name= "ken is good";
console.log(name.indexOf(k)); //1

(5)toLowerCase(變小寫)

let name= "KEN";
console.log(name.toLowerCase()); //ken

(6)toUpperCase(變小寫)

let name= "ken";
console.log(name.toUpperCase()); //KEN

(7)split (陣列搜尋)

let name = “ken is good”;
console.log(name.split(“ “)); 
//['ken', 'is', 'good']
//0: "ken"
//1: "is"
//2: "good"
//length: 3
--------------------------------
let name = “ken”;
console.log(name.split(““));
//['k', 'e', 'n']
//0: "k"
//1: "e"
//2: "n"
//length: 3

3. Boolean