[英]javascript properties of methods
Is it possible in javascript to set properties inside methods? 是否有可能在javascript中设置方法内部的属性?
For example 例如
function Main() {
this.method = function() {
this.parameter = 'something_relevant'
}
}
var p = new Main()
p.method()
console.log(p.method.parameter)
I tried this and it logs 'undefined'. 我试过了,它记录为“未定义”。 Is it about scope?
关于范围吗?
Inside method()
you're setting a property of the object on which the method is called rather than on the function object representing the method. 在
method()
内部,您要设置在其上调用方法的对象的属性,而不是在表示该方法的函数对象上的属性。
This shows the difference inside the method: 这显示了方法内部的区别:
this.method = function() {
this.parameter = 'abc'; // Set parameter on the object on which method() is called
this.method.parameter = 'xyz'; // Set parameter on the object representing the method itself
};
This shows the difference in accessing the property after the method is called 这表明在调用方法后访问属性的区别
p.method();
console.log(p.parameter); // Display property of the object p, equals 'abc'
console.log(p.method.parameter); // Display property of the function object representing method(), equals 'xyz'
You should decide whether you need a property on the function object or on p
object. 您应该决定是否需要函数对象或
p
对象上的属性。 Note that the function object may be shared by a number of objects created by the Main()
constructor. 注意,函数对象可以由
Main()
构造函数创建的许多对象共享。 Hence it will behave in a manner somewhat similar to a static member in languages like C++ or Java. 因此,它的行为与类似于C ++或Java的静态成员的行为类似。
If you intend to use property defined on the object, your code should look similar to this: 如果打算使用在对象上定义的属性,则代码应类似于以下内容:
function Main() {
this.method = function() {
this.parameter = 'something_relevant'; // Set property on object on which method() is called.
};
}
var p = new Main();
p.method();
console.log(p.parameter); // Read property from object p.
If you intend to use a property defined on the function object representing method()
, your code should look similar to this: 如果打算使用在表示
method()
的函数对象上定义的属性,则代码应类似于以下内容:
function Main() {
this.method = function() {
this.method.parameter = 'something_relevant'; // Set property on function object representing method().
};
}
var p = new Main();
p.method();
console.log(p.method.parameter); // Read property from the function object.
Functions are objects basically, so just set it like you get it: 函数基本上是对象,所以只要像得到它一样进行设置即可:
this.method = function() {
};
this.method.parameter = 'something_relevant';
Also, don't eliminate semicolons after expressions. 另外,不要在表达式后消除分号。
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