Neues Node.js-Buch
Philip Ackermann

Philip Ackermann

📚Fachbuchautor 🚀CTO der Cedalo AG 📓Blogger

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Apply pseudoclassical inheritance

Problem

You want to use pseudoclassical inheritance, i.e., create a “class” as “subclass” of another “class”.

Ingredients

  • 2 or more functions
  • the prototype property
  • the call() method

Directions

  1. Define a function intended to be a constructor function (this will be the “superclass”).

    function Animal(color) {
  this._color = color;
}
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Convert arguments object to array

Problem

You want to convert the array-like object arguments to a real array.

Ingredients

  • the Array prototype
  • the slice() method
  • the call() method

Directions

  1. Given: a function that takes different parameters and accesses them via the arguments object.

    function printAllArguments() {
  let values = arguments;
  for(let i=0; i<values.length; i++) {
    console.log(values[i]);
  }
}
printAllArguments(2, 3, 4);
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Emulate block level scope

Problem

You want to emulate block level scope in ES5 to prevent naming conflicts.

Ingredients

  • Immediately-Invoked Function Expression (IIFE)

Directions

  1. Given: some code that you want to put in a block.

    var aVariable = 2345;
// Block should start here
var aVariable = 4711;
console.log(aVariable);      // should print 4711
// Block should end here
console.log(aVariable);      // should print 2345, but prints 411
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