Classes
Class的組成元素:
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Constructor
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Prototype methods:
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Static methods: 不需要New class就可以使用, 類似C#的Static
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| class Polygon {
constructor(height, width) {
this.height = height;
this.width = width;
}
get area() {
return this.calcArea()
}
calcArea() {
return this.height * this.width;
}
static distance(a, b) {
const dx = a.x - b.x;
const dy = a.y - b.y;
return Math.sqrt(dx*dx + dy*dy);
}
}
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Hoisting: Class並沒有Hoisting特性，所以需要先定義才可以使用，這點須注意
Class inheritance
Class也可以有繼承的性質
範例
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| class Animal {
constructor(name) {
this.name = name;
}
speak() {
console.log(this.name + ' makes a noise.');
}
}
class Dog extends Animal {
speak() {
console.log(this.name + ' barks.');
}
}
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Super的用法
Super用來呼叫Parent的function
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| class Cat {
constructor(name) {
this.name = name;
}
speak() {
console.log(this.name + ' makes a noise.');
}
}
class Lion extends Cat {
speak() {
super.speak(); // <= this call Cat's speak function
console.log(this.name + ' roars.');
}
}
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