var html = ''; What does it mean to the code and why it's here?

Question

Hi everybody, the whole course was very clear to me, but there is a one little thing i can't understand. Why do we use this "var html = ''; " and why we use it here for instance: html += '<div style="background-color:' + rgbColor + '"></div>'; .

It's a string and it's empty, however it's still a string right?

Aparently it made me really curious and i tried different things and values with it, and everytime it was a mess, so i could not understand the idea behind it.

Why it turns into a mess when we do this for example : html = '<div style="background-color:' + rgbColor + '"></div>'; . ??

Please help =)!

Answer 1 · 2016-09-17T09:12:03Z

September 17, 2016 9:12am

Hi there! Yes, it's an empty string. But before you assign the empty string to it, it isn't. When you do something like var myString; JavaScript sets aside a piece of memory for that variable. But the variable at this point is undefined. So if you don't initialize it to an empty string and then try to append to it, it can have unexpected consequences. It's generally a good idea to initialize any variable you know will hold a string with an empty string because of this. And because this is now an empty string as opposed to undefined, you can continue appending strings to it without problem. Hope this helps!

edited for additional note

Also when you say html = you are overwriting the string entirely with the string on the right side of the equals. But when you do html += you are appending that string to the end of the string that was already stored there.

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Sergey Golubev

Sergey Golubev

var html = ''; What does it mean to the code and why it's here?

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Jennifer Nordell

Jennifer Nordell

Sergey Golubev

Sergey Golubev