<!DOCTYPE HTML> <html> <head> <title>Test es6</title> </head> <body> <h2>Welcome to es6</h2> </body> <script type="text/javascript"> //1. Variable let const var a = 1; { let a = 3; console.info('let a',a); //3 } console.info('var a',a); //1 let b = 3; //let b = 4; //Identifier 'b' has already been declared (in the block-level scope defined by let, the same variable name cannot be defined repeatedly) const A = 3;//Variables are generally capitalized, indicating constants //A = 4; //Assignment to constant variable.(Const defined constants are not allowed to be modified) //const A = 4;//Identifier 'A' has already been declared (same as let, duplicate definitions are not allowed in the scope) //2.for of forEach loop { let b = 'welcome use EcmaScript6'; b = b.split(' '); for(var i of b){ console.log(i);//welcome use EcmaScript6 } b.forEach(function(r){ console.log('forEach',r); }); b.forEach(r => console.log('forEach => ',r)); } //3. About arrow functions //The short form of the function (parameters) => the function body var arrowFunction1 = function(){ //es5 writing return 'I`m a arrow function'; } var arrowFunction2 = () => 'I`m a arrow function';//es6写法 console.info('arrowFunction:',arrowFunction1()); console.info('arrowFunction:',arrowFunction2()); let arr = ['a','b','c']; arr.map((vari) => console.info('arrow return ',vari)); let getFinalPrice = (price, tax=0.7) => console.info(price + price * tax); getFinalPrice(500); // 850 //destruct var [arrA,arrB,arrC] = arr; //Assign the values of the array to the variables in [] in order console.log(arrA,arrB,arrC); //a,b,c var [arrC, arrA] = arr; console.log (arrA, arrC); // b, a var a = 1,bb = 4; [a,bb] = [bb,a]; console.log([a,bb])//4,1 can be used to exchange arrays without defining intermediate temporary parameters //...operator //Spread operation extension console.info (... [1,2,3,4]) // 1 2 3 4 function foo(x,y,z){ console.log(x,y,z); } foo(...[1,2,3,4]);// 1 2 3 foo(...[{1:4},{2:3}]);//{1:4} {2:3} //Rest operation remaining function boo(...args){ console.info(args); } boo(1,2,3,4,5,6)//[1, 2, 3, 4, 5, 6] //` to assemble a bunch of variables and string ${} to replace variables var str1 = 'XiaoMing'; console.info(`my name is ${str1}`); //Class constructor inheritance (based on prototype chain) class Car { constructor() { console.info('this is car'); } move(){ console.info('moving'); } } var car1 = new Car(); car1.move(); class AutoCar extends Car{ constructor() { super(); console.info('this is auto Car'); } } var autoCar = new AutoCar (); autoCar.move(); </script> </html>
Preliminary learning ecmaScript6
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