taking return value from callback function in js code example

Example 1: javascript getposts callback

// *** JS GetPosts Callback ***

    run.addEventListener('click', () => {
        window.lib.getPosts((error, articles) => {
          	return (error ? console.log(error) : console.log(articles));
            /* Alternate syntax
          	 if (error) {
                 console.log(error);
             }
             for (elem of articles) {
                 console.log(elem);
            }; // => console.log(articles); similarly works
            /*
        });
    })

Example 2: how to pass callback function in javascript

function functionOne(x) { alert(x); }

function functionTwo(var1, callback) {
    callback(var1);		
}

functionTwo(2, functionOne);