如果忘記放上new關鍵字, JavaScript會直接執行物件, 此物件會被設為undefined
因此習慣上會把要當成建構子的函數首字大寫
//建立物件 function Person() { this.firstname = 'John'; this.lastname = 'Doe'; } //建立空物件 //呼叫person, 並把this指到person上 var john = Person(); //印出undefined console.log(john) //出現錯誤 Person.prototype.getFullName = function() { return this.firstname + ' ' + this.lastname }
Last updated 4 years ago
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