Object.prototype using 'this'

Question

This might be basic, it might not be possible, I might be misunderstanding totally but I am a beginner trying to understand how adding methods to objects using Object.prototype works.

The best way to explain my question is to show firstly show the following:

Object.prototype.printHTML = function() {
    alert(this.innerHTML);
};

this seems to refer simply to Object.prototype.printHTML (alerting the HTML of exactly what is after the = sign in the above.

My question is , can you refer directly to the Object used?

so, the below would alert "Test Paragraph":

<body>
<p id='test'>Test Paragraph</p>

<script>
Object.prototype.printHTML = function() {
    alert(this.innerHTML);
};

document.getElementById("test").printHTML; //this would alert "Test Paragraph"
//currently alerts "function() {alert(this.innerHTML);}
</script>
</body>

I understand this example is pointless (because document.getElementById("test").innerHTML; gives me exactly what I would need for this) but I am just trying to understand creating methods using Object.prototype and I cannot figure out how to access the Object the method is being run on.

Thanks

Answer 1

You are really close, instead do this

<body>
<p id='test'>Test Paragraph</p>

<script>
Object.prototype.printHTML = function() {
    alert(this.innerHTML);
};

document.getElementById("test").printHTML(); //<--- HERE WE ADD THE PARENTHESIS
//currently alerts "function() {alert(this.innerHTML);}
</script>
</body>

You were accessing printHTML as a property rather and a function and executing it. Hence why you got the function as text.

Object.prototype using 'this'

Question

1 answers

solution1
2 ACCPTED 2016-05-15 10:24:15

Object.prototype using 'this'

Question

1 answers

solution1 2 ACCPTED 2016-05-15 10:24:15

solution1
2 ACCPTED 2016-05-15 10:24:15