var car = {
"wheels":4,
"engines":1,
"seats":5
};
var motorBike = {
"wheels":3,
"engines":1,
"seats":2,
// Only change code below this line.
};
2-Construct JavaScript Objects with Functions
構造函數通常第一個字大寫，用來區分一般函數
this 指向創建出來的對象
var Car = function() {
this.wheels = 4;
this.engines = 1;
this.seats = 5;
};
// Only change code below this line.
var MotorBike = function() {
this.engines=1;
this.wheels=2;
this.seats=2;
};
3-Make Instances of Objects with a Constructor Function
用 new function() 來創建一個實力 instance
var Car = function() {
this.wheels = 4;
this.engines = 1;
this.seats = 5;
};
// Only change code below this line.
var myCar = new Car();
myCar.nickname = "Chacha";
4-Make Unique Objects by Passing Parameters to our Constructor
var Car = function(wheels, seats, engines) {
//Change this constructor
this.wheels = wheels;
this.seats = seats;
this.engines = engines;
};
//Try it out here
var myCar = new Car(2, 2, 1) ;
5-Make Object Properties Private
建構函數內，自己的函數稱為方法，自己的特徵稱作屬性(忘了)
讓私有資料只能透過方法存取
var Car = function() {
// this is a private variable
var speed = 10;
// these are public methods
this.accelerate = function(change) {
speed += change;
};
this.decelerate = function() {
speed -= 5;
};
this.getSpeed = function() {
return speed;
};
};
var Bike = function() {
// Only change code below this line.
var gear = 2;
this.getGear = function(){
return gear;
};
this.setGear = function(change){
gear = change;
return gear;
};
};
var myCar = new Car();
var myBike = new Bike();
myBike.getGear(3);
6-Iterate over Arrays with map
有點詭異的迴圈
.map() 括號中是個 callback function
第一個參數是處理的元素，第二個是 index，第三個是陣列
好吧其實我看不太懂
var oldArray = [1,2,3,4,5];
// Only change code below this line.
var newArray = oldArray.map(function(val){
return val+3;
}
);
7-Condense arrays with reduce
將陣列變成一個數字
reduce() 有兩個參數
第一個，callback function 有兩個參數，累加器和當前值
第二個，是初始值
var array = [4,5,6,7,8];
var singleVal = 0;
// Only change code below this line.
singleVal = array.reduce(function(previousVal, currentVal){
return previousVal+currentVal;
},0);
8-Filter Arrays with filter
var oldArray = [1,2,3,4,5,6,7,8,9,10];
// Only change code below this line.
var newArray = oldArray.filter(function(val){
return val<6;
});
9-Sort Arrays with sort
a-b 是正序排
b-a 是逆序排
var array = [1, 12, 21, 2];
// Only change code below this line.
array.sort(function(a, b){
return b-a;
});
10-Reverse Arrays with reverse
var array = [1,2,3,4,5,6,7];
var newArray = [];
// Only change code below this line.
newArray = array.reverse();
11-Concatenate Arrays with concat
var oldArray = [1,2,3];
var newArray = [];
var concatMe = [4,5,6];
// Only change code below this line.
newArray = oldArray.concat(concatMe);
delimiter 分隔符號
12-Split Strings with split
var string = "Split me into an array";
var array = [];
// Only change code below this line.
array = string.split(' ');
13-Join Strings with join
var joinMe = ["Split","me","into","an","array"];
var joinedString = '';
// Only change code below this line.
joinedString = joinMe.join(" ");