Typejavascript notes----strings, arguments, functions, expressions, Loops

A new character of string--double 丿 (apostrophe) declaration string
, multi-line string
var myName = ' Fang
My Hao Li
Jsk c SDF '//this will not Error.
, String templates
Console.log (' Qsdaf ${myname} ')
Console.log (' Qsdaf ${myname ()} ')//functions and variables can be written directly inside the ${}
Console.log (' <div>
<span>${myName}</span>
</div> ')//so that it can be written quickly, without a plus connection;
, auto-split character string
Function Test (a,b,c) {
Console.log (a);
Console.log (b);
Console.log (c);
}
var myname = ' Ni hao ';
var getage = function () {
return 18
}//the following call, A is an array [' hello my name is ', ', im ', ']; B is ' Ni hao '; c is 18; that is, it is separated by a variable
Test ' Hello my name is ${myname},im ${getage ()} ';
Ii. New characteristics of parameters
1. parameter type--use a colon after the parameter name to specify the type of the parameter
, any can be of any type
var myname:any = 18;
, string String type
var myname:string = "zhang san"
, number numeric type
var my:number = 20
, Boolean Boolean type
var Name:boolean =true
Function Test (name:string): String {
Return ""
}//means that a parameter can only be a string, and the return value of a function can only be a string;
, Custom types
Class Person {
name:string;
age:number;
}
var Zhangsan:P erson = new Person ()
Zhangsan.name = "zhailiang";
Zhangsan.age = 18
2. parameter default value--specify The default value of the parameter with an equal sign after the parameter declaration
var my:string = "fang";
Function Test (a:string,b:string,c:string= "wo") {
Console.log (a)
Console.log (b)
Console.log (c)
}
test{' SFA ', ' sss ', ' ASD '}//do not give default values must give 3 parameters otherwise will error; parameters with default values can not be written (but must be written on the last Side)
3, optional Parameters--after The parameter declaration of the method with a question mark to indicate that this parameter is an optional parameter
Function Test (a:string,b?:string,c:string= "wo") {
Console.log (a);
Console.log (b);//error when B.length
Console.log (c);
}
test{' SFA '}//this will not error, B is undefined; and a note. as with the default parameters, optional parameters must be written after the required write parameter
Iii. new features of functions
1. Rest and spread operator (...) )--used to declare any amount of method parameters
function Func1 (.... Args) {
Args.foreach (function (arg) {
Console.log (arg);
})
}
Func1 (func1) (1,3,4,5,6)//forward Use
function Func2 (a,b,c) {
Console.log (a);
Console.log (b);
Console.log (c);
}
var args = [1,2],ARGS1 = [5,6,7];
Func1 (... args); func1 (... args1)//reverse
2. Generater function--control function Execution process, manual pause and Recovery code execution
function* dosomething () {
Console.log ("start");
Yield
Console.log ("finish")
}
var fun1 =dosomething ();
Func1.next ();//will stop in the yield place
Func1.next ();
3. Destructuring destructor expression--to disassemble an object or an array into any number of variables through an expression
function Getstock () {
return {
Code: "IBM",
price: {
price1:100,
price2:200
}
}
}
var {code:codex,price:{price2}} = Getstock ();
Console.log (codex);
Console.log (price2)//disassemble from Object
var array = [1,2,3,4];
var[number1,number2] = array;
Console.log (NUMBER1)//1
Console.log (NUMBER2)//2
var[,,, number1,number2] = array;
Console.log (NUMBER1)//3
Console.log (NUMBER2)//4
var[number1,number2,... others] = array;
Console.log (NUMBER1)//1
Console.log (NUMBER2)//2
Console.log (others)//[3,4]
Iv. Expressions and Loops
1. Arrow expression--used to declare anonymous function, eliminate this pointer problem of traditional anonymous function
var sun = (arg1,arg2) =>arg1+arg2//only One line does not have to write Curly braces, also does not have to write the return keyword
var Sun =arg3 =>console.log (arg3)//do not write parentheses when there is only one parameter
var MyArray = [1,2,3,4,5,6];
Console.log (myarray.filter (value =>value%2 = = 0))

function Gerstock (name:string) {
THIS.name = name;
SetInterval (() = {
Console.log ("name is:" + this.name);
},1000)
}
var stock = new Getstock ("IBM")//can be seen typed as "name is:ibm", eliminating the traditional anonymous function this pointer problem, if you write with ES5 can not get IBM
2, ForEach (), for in and for
var MyArray = [1,2,3,4];
Myarray.desc = ' Four number ';
Myarray.foreach (value=>console.log (value))//ignores Its properties and cannot be interrupted
For (var N in MyArray) {
Console.log (n)//key and attribute of key-value pairs typed 0,1,2,3,desc
Console.log (myarray[n])//each Value played
}
For (var N of MyArray) {
If (n>2) break;
Console.log (n)
}//and foreach can just be interrupted by a break, a collection, an array can be used, or it can be used on a string, which will print every character of the String.

Typejavascript notes----strings, arguments, functions, expressions, Loops