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1. 介绍 JavaScript ES6

介绍JavaScript​

  • Netscape Navigator, 90年代在浏览器界有统治地位的公司 Netscape Navigator

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Java和 JavaScript 的区别​

Javascript Alerts - Adding Behaviour to websites​

最全的写法是window.alert("Hello world");

但是大多数都写成: alert("Hello world");

就像《The Elements of Style》

Data Types​

alert("Hello"); 里面的 "Hello"就是 string 类型

类似的数据类型有：

  • number
  • boolean
  • string

Javascript Variables​

  • 我叫 xxx

  • 我住在 xxx

  • 我的兴趣是 xxx

  • prompt("What is your name?");

  • var myName = "Baozige";

  • var yourName = prompt("What is your name?");

Javascript Variables Exercise Start​

var a = "3";
var b = "8";

// 交换 a b 的内容

Naming and Naming Conventions for Javascript Variables​

  • 要有意义
  • 不要用关键字
  • 字母，数字，$, _,其他的都不行

String Concatenation​

+

String Lengths and Retrieving the Number of Characters​

var name = "Baozige";
var nameCount = name.length;


  • www.twitter-character-counter.com

Slicing and Extracting Parts of a String​


var name = "Angela";
name.slice(0,1);

toUpperCase​


var name = "Baozige";
name = name.toUpperCase();

Challenge: Chaging String Casing Solution​

把人名首字母大写

Basic Arithmetic and the Modulo Operator in Javascript​

  • /

  • %

  • *

  • +

  • -

  • 优先级

  • 狗的年纪转换到人的年纪

humanAge = (dogAge - 2)x4 + 21

Increment and Decrement Experssions​

  • x++ = x = x+1

  • x-- = x = x-1

  • x+=2 = x=x+2

var x = 3;
var y = x++;
y += 1;

Functions Part1: Creating and Calling Functions​

function getMilk() {
    // ...
}

Functions Part 1 Challenge - The Karel Robot​

  • https://stanford.edu/~cpiech/karel/ide.html
function main(){
   beepersRight();
   goUpTurnLeft();
   beepersLeft();
   goUpTurnRight();
      beepersRight();
   goUpTurnLeft();
   beepersLeft();
   goUpTurnRight();
      beepersRight();
}
 
function goUpTurnRight() {
   turnRight();
   move();
   turnRight();
}
 
function goUpTurnLeft() {
   turnLeft();
   move();
   turnLeft();
}
 
function beepersRight() {
   putBeeper();
   move();
   move();
   putBeeper();
   move();
   move();
   putBeeper();  
}
 
function beepersLeft() {
   move();
   putBeeper();
   move();
   move();
   putBeeper();
   move();
}
function getMilk() {   
  console.log("leaveHouse");
  console.log("moveRight");
  console.log("moveRight");
  console.log("moveUp");
  console.log("moveUp");
  console.log("moveUp");
  console.log("moveUp");
  console.log("moveRight");
  console.log("moveRight");
  console.log("moveLeft");
  console.log("moveLeft");
  console.log("moveDown");
  console.log("moveDown");
  console.log("moveDown");
  console.log("moveDown");
  console.log("moveLeft");
  console.log("moveLeft");
  console.log("enterHouse");
}

function lifeInWeeks(age) {
    
/************Don't change the code above************/    
    
    //Write your code here.
    
    var days = (90-age)*365;
    var weeks = (90-age)*52;
    var months = (90-age)*12;
    console.log("You have " + days + " days, " + weeks + " weeks, and " + months + " months left.")
    
    
    
/*************Don't change the code below**********/
}



Functions Part 3: Outputs & Return Values​

BMI Calculator​

BMI = weight(kg)/height2(m2)


//Create your function below this line.
//The first parameter should be the weight and the second should be the height.

function bmiCalculator(weight, height){
    return Math.round(weight/(height*height));
    return Math.round(weight/Math.pow(height, 2));

}


/* If my weight is 65Kg and my height is 1.8m, I should be able to call your function like this:

var bmi = bmiCalculator(65, 1.8); 

bmi should equal 20 when it's rounded to the nearest whole number.

*/


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