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JavaScript jQuery Basics Working with jQuery Collections Looping through a jQuery collection

Posted by Zhenghao He
Zhenghao He
Courses Plus Student 2,389 Points

Why can't arrow function work in this case

Hi guys, I was following along with the video and there was this snippet

$('a').each(function(){
  const url = $(this).attr('href');
  $(this).parent().append(`(${url})`);
});

I tried to rewrite this by using arrow function as 

$('a').each(()=>{
  const url = $(this).attr('href');
  $(this).parent().append(`(${url})`);
});

but it didn't work. Why is that?

3 Answers

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

Arrow functions are not exact replacements for conventional functions and work a bit differently. One of the differences is that arrow functions do not establish a value for "this".

See this MDN page for more information on arrow functions and how they are different.

You can usually refactor the code to use passed-in argument(s) instead of "this". In this example:

$('a').each((_,a)=>{
  const url = $(a).attr('href');
  $(a).parent().append(`(${url})`);
});
Zhenghao He
Zhenghao He
Courses Plus Student 2,389 Points

oh I see, thanks!

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

A single underscore makes a convenient placeholder, and I use it to imply that an argument is not used.

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

No, that's not part of the course. I was just explaining why I used it in my example.

Elena Man
Elena Man
21,092 Points
Elena Man
Elena Man
21,092 Points

Thank you! I was having the same issue and didn't know where I was wrong.