TS environment installation and test installation
① : Install Node. js and NPM
Use node -v and NPM -v to check whether the installation is successful. If the version number is displayed, the installation is successful.
② : Install TS
Command: NPM install -g typescript
Check the installation: Run the TSC -v command to display the version number, indicating that the installation is successful
Ii.TS basic use and vscode automatic compilation Settings
1: Basic use
① : Create the 1.ts file
let aa : String='Niu Zhikun'; alert(aa);Copy the code② : Run the TS file on the terminal command line
Command: TSC file path
After execution, the corresponding JS file is generated
2: enable vscode to compile automatically
① : Use TSC –init command in the root directory to generate tsconfig.json file
② : Cancel the outDir comment in the JSON file and set the path name of the saved folder
③ : select the top terminal of vscode -> run tasks -> TSC monitor
Three: TS variable declaration
Variable declaration format in TS:
Let/const /var Variable name: Data type = variable value Short let variable name = variable value
Joint type let variable names: data type 1 2 | | data type… = a variable’s value
The variable data type cannot be changed after it is specified and an error will be reported
String: let STR: string = ‘STR’/” STR “/ · STR ·;
Boolean: let bool: Boolean = true/false;
Note: Boolean values in TS cannot use 0/1 to represent true and false
Let num:number = 1;
null : let nul:null = null;
undefined : let nud:undefined =undefined;
Array: let arr: element data type [] = [element of specified data type,……]
Let arr: Array< element data type > = [element of specified data type,……]
Tuple: An array that specifies the data type and number of elements. Since arrays in TS cannot contain different types of elements, tuples can be used instead
Let arr: [string, number, number] = [‘ 123 ‘, 14, 32]
When defining tuple data, there must be a one-to-one correspondence according to the specified element data type and quantity
Access tuple data as an array
Enum: Enumeration can be understood as an object in JS. The declaration mode is the literal declaration of the object
Method 1: enum Enumeration name {Enumeration item = Enumeration value,……. } Enumeration entries are alphabetic and numeric. Enumeration values are integer numbers
Method 2: enum Enumeration name {Enumeration item,……. } Enumeration items default to generate the corresponding enumeration value, which is the subscript of the item, starting at 0
Any: indicates that the data type of the retrieved data cannot be determined. This is common in DOM fetching
let a: any =document.getElementById(‘id’);
Viod: Used to define methods that have no return value
function alerts(): void { alert(“Hello ts”); }
function getNum(): number{ return 1; }
Four functions
Function declaration
Function Function name (parameter 1: type,….) : Return value type {} The number of participating parameters must be of the same type
Function Name () : return value type {}
Function name (argument) Function name ()
Optional parameter function Function name (parameter 1? : types,…). : Return value type {}
Call with arguments: function name (argument) No arguments: function name ()
Function Function name (parameter 1: type = default,….) : Return value type {}
Function Function name (parameter 1: type,… Parameter 2: type []) : return value type {}
Five categories
The class name of the class {
/ / field
Variable name: type; .
// constructor
Constructor (Variable name: type,….) {
This. Variable name = variable name; .
}
// disp():void {
do something…..
}
}