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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops The Refactor Challenge

Enemuo Felix
Enemuo Felix
1,895 Points
Posted by Enemuo Felix
Enemuo Felix
1,895 Points

Why html+= and not html = ?

I know += is used to increase count at each iteration but why did dave use it in this case

html+= 'div style='background-color: ' + rgbcolor + ' ''></div> ' ;

2 Answers

Katie Wood
Katie Wood
19,141 Points

Hi again,

Usually, if you're trying to write in multiple html elements at one time or generate a whole code block, you build up the html code one piece at a time and then write it all to the document in one line. I believe in this example, there is a line where he writes the html variable into the html document.

The html += means that we're adding on to the existing html variable to generate the whole code block we actually want to add, piece by piece. If we used html =, it would overwrite what's already there and just set the html variable to that one line.

Does that make sense?

Enemuo Felix
Enemuo Felix
1,895 Points
Enemuo Felix
Enemuo Felix
1,895 Points

Thanks Again. It does

nick black
nick black
5,578 Points
nick black
nick black
5,578 Points

html += is equivalent to html = html + "new content".

a.) var html = "cat";
b.) html = "dog";
c.) html += " dog";

a. console.log(html) // outputs the string, "cat"
b. console.log(html) // outputs the string, "dog"
c. console.log(html) // outputs the string, "cat dog"

// You will also see this used a lot when incrementing a variable.

x = 0;
x += 1;   // equivalent to x = x + 1;