Does concat method join or extracts values in arrays?... The code provided outputs JS only...

Question

ar c1 = ["HTML", "CSS"];
var c2 = ["JS", "C++"];
var courses = c1.concat(c2);

document.write(courses[2]);

Answer 1

concat returns a new concatenated array, that's why it was assigned to "var courses" in the example you provided

Answer 2

[Aside]
You may have pasted this into a webcode's HTML tab (use [JS] and fix 'ar' to be 'var').