Function Function arrow e_ _

function

Arrow function

	// variable and there is a direct return of 
	var = F = V> V; 
	// equivalent 
	var = function F (V) { 
	  return V; 
	}; 
	// needs no arguments or return of a plurality of parameters not directly 
	var = SUM (num1, num2) => { 
		the let K = + num1 num2; 
		return K; 
	}; 
	// equivalent 
	var function = SUM (num1, num2) { 
		the let K = + num1 num2; 
		return K; 
	};

this function problems arrow

Plug one call of use

		var a = 10;
		function call_1() {
		　　console.log(this.a);
		}
		var call_obj = {
		　　a: 20
		}
		call_1();//10
		call_1.call(call_obj);//20 this指向call_obj	

this function on the arrow did not understand ...... Do not believe your own summary

	// function directly written by the little arrow can point call obj1.fn_new (); this execution window; 
	var = TS 'global'; 
	const = {OBJ1 
		TS: "OBJ1", 
		fn_new: () => { 
			Console .log (this.ts); 
		} 
	} 
	obj1.fn_new (); // global    
	
	// bit regardless of how many layers can directly point to point is that this window 
	const = {OBJ3 
		TS: "OBJ3", 
		fn_obj: { 
			TS: " obj3_3 ", 
			fn_new_2: () => { 
					the console.log (this.ts); 
			} 
		}	 
	} 
	obj3.fn_obj.fn_new_2 () // global

	// If the arrow is only obtained after a function used () diao call. 
	var ts = 'global'; 
	const obj2 = { 
		TS: "obj2", 
		fn_new_1: function () { 
			the console.log (this.ts); 
			return () => { 
				the console.log (this.ts); 
			} 
		} 
	} 
	 let fn = obj2.fn_new_1 (); // obj2 fn is a function of the arrow by () call before they get 
	 the Fn (); // obj2 
	 
	 // arrow function of this generation with the function of the arrow function (here is fn_new_1 function) this refers to the same 
	 // this fn_new_1 here is a function call directed to its target fn_obj 
	 // call this change also followed when the function becomes an arrow 
	const = {OBJ3 
		TS: "OBJ3", 
		fn_obj: { 
			TS: "obj3_3", 
			fn_new_1 : function () { 
				the console.log (this.ts); 
				return () => { 
					the console.log (this.ts); 
				}
			}
		}	 
	} 
	Let fnn = obj3.fn_obj.fn_new_1 (); // obj3_3 
	fnn (); // obj3_3

Some magic

	// arrow arrow this function itself is not a function of this inner layer is equal to the multiple nested outer this 
	var A = 2; 
	var K = { 
		A:. 1, 
		FF: function () { 
			the console.log (this.a) 
			return () => { 
				the console.log (this.a); 
				return () => { 
					the console.log (this.a); 
				}	 
			} 
		} 
	} 
	the let k.ff F1 = (); //. 1 
	the let F2 = F1 (); //. 1 
	F2 (); //. 1

	// use settimeout feeling is not right in front of the ideas regardless of the timer on the right 
	
	// call the function foo only when the timer function will start to take effect arrow   
	// arrow with the function of this function to generate arrow function (here is a function foo) of this same point 
	
	var ID = 10; 
	function foo () { 
		the console.log (this.id); // 10 
	  the setTimeout (() => { 
	    the console.log ( 'ID:', this.id) ; 
	  }, 100); 
	} 
	foo (); // foo 10 points of this window (because window.foo ()) 
	
	var KK = { 
		ID: 20 is, 
		Fuu: function () { 
			 the setTimeout (() => { 
			    Console. log ( 'ID:', this.id); 
			  }, 100); 
		} 
	} 
	kk.fuu (); // Fuu 20 is a function of this arrow will point to point kk kk

---

arrow function arguments

	// Get argument 
	function FUNC (A, B, C) { 
		the console.log (arguments); 
		// [. 1, 2,. 3, the callee: ƒ, the Symbol (Symbol.iterator): ƒ] 
		 the console.log (arguments [ . 4]); // undefined 
		 the console.log (arguments [. 3]); //. 4 
		} 
	FUNC (1,2,3,4) 

	//...a result of a so unlock equal to 2,3 equal to [l, 2,3] 
	the let Fn = (... a) => { 
		the console.log (a); 
	} 
	Fn (l, 2,3); // [. 1, 2,. 3]