Accessing object

1 
var someObj = {

  propName: "John",

};

function propPrefix(str) {

  var s = "prop";

  console.log(s + str);   //output "propName"

}

i got confuse about the the output of the console. can anyone pls explain

2

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

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4

Can you give more detail about what is happening that confuses you?

5

below is the details from freecodecamp

var someObj = {
  propName: "John"
};
function propPrefix(str) {
  var s = "prop";
  return s + str;
}
var someProp = propPrefix("Name"); // someProp now holds the value 'propName'
console.log(someObj[someProp]); // "John"

to know the value of the “return s+ str” i had to console log it and i was amazed at the out but don’t understand its so. Hence i needed some to help me out

6

Ok.
At this point, I’m assuming that you’re comfortable with getting properties from objects.

Are you comfortable with how all of these work?

var someObj = {
  propName: "John"
};
console.log(someObj.propName);

var someObj = {
  propName: "John"
};
console.log(someObj['propName']);

and

var someObj = {
  propName: "John"
};

var nameKey = 'propName';
console.log(someObj[nameKey]);
7

I absolutely understand it, i know how it works

8

Cool. So the only part added here is the propPrefix() function.
propPrefix() takes a string and returns a modified string. In this case, it is built on the assumption that all of the property names in someObj all follow the same pattern: they start with “prop”. Based on that assumption, if I wan the name value, I would need “propName”. If I wanted the address it would probably be “propAddress”.
The propPrefix()function takes in a string as a parameter, which should be the unique part of the property name. The function then just returns a string with “prop” added to the front.

That means that we can do

var someObj = {
  propName: "John"
};
var someProp = propPrefix("Name");
console.log(someObj[someProp]);

or even

var someObj = {
  propName: "John"
};
console.log(someObj[propPrefix("Name")]);

and have it work exactly the same.

Let me know if I completely missed the part that you meant to ask about. :smiley:

9

Your explanation is clear and precise. Thank you so much. let me get back on the course…

1 Like
10

I’m glad I could help. Happy coding!