static

語法

static methodName() { ... }

敘述

Static methods are called without instantiating their class and are also not callable when the class is instantiated. Static methods are often used to create utility functions for an application.

範例

下面的範例示範了許多東西。他示範了如何在一個可以有子類別的類別中實作一個靜態方法。最後示範了靜態方法在什麼情形下正確與錯誤的呼叫。

class Triple {
  static triple(n) {
    n = n || 1; //should not be a bitwise operation 
    return n * 3;
  }
}

class BiggerTriple extends Triple {
  static triple(n) {
    return super.triple(n) * super.triple(n);
  }
}

console.log(Triple.triple());        // 3
console.log(Triple.triple(6));       // 18
console.log(BiggerTriple.triple(3)); // 81
var tp = new Triple();
console.log(tp.triple());             // 'tp.triple is not a function'.

規格

瀏覽器相容性

你可能會需要看看

• class expression
• class declaration
• Classes