When Do JavaScript Object Variables Need 'this'?

Do Javascript Object Variables Require "this"?

In Javascript, the concept of classes differs from languages like C . Class-based inheritance is lacking, making way for prototypical inheritance. Objects and their properties play a crucial role.

When constructing an object using a constructor function, the "this" keyword grants access to the object's properties. Consider the following example:

function Foo() {
    this.bar = 0;
}

In this constructor, the "this" keyword associates the "bar" property with the created object. Failure to use it would result in the error "bar is undefined."

However,开发者发现了一个技巧，使用构造函数作为闭包，创造私人"属性"：

function Foo() {
    var bar = "foo";
    this.getBar = function getter() {
        return bar;
    };
}

In this example, the variable "bar" is declared locally, while "getBar" is a privileged method that accesses it. This technique allows the creation of private variables that cannot be modified externally.

It's essential to note that methods declared on the prototype do not have access to local variables within the constructor. However, they can utilize privileged methods. In the following code, the prototype method "getFooBar" uses the "getBar" method to concatenate a suffix:

Foo.prototype.getFooBar = function() {
    return this.getBar() + "bar";
}

This allows for the creation of both public (prototype methods) and private (privileged methods) properties within a single object.It's important to consider memory usage as privileged methods create distinct function objects with different scope chains. For large amounts of instances, prototype methods are preferred.

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