freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.english.md

id, title, challengeType, isHidden, videoUrl, forumTopicId

id	title	challengeType	isHidden	videoUrl	forumTopicId
56533eb9ac21ba0edf2244be	Global Scope and Functions	1	false	https://scrimba.com/c/cQM7mCN	18193

Description

In JavaScript, scope refers to the visibility of variables. Variables which are defined outside of a function block have Global scope. This means, they can be seen everywhere in your JavaScript code. Variables which are used without the var keyword are automatically created in the global scope. This can create unintended consequences elsewhere in your code or when running a function again. You should always declare your variables with var.

Instructions

Using var, declare a global variable named myGlobal outside of any function. Initialize it with a value of 10. Inside function fun1, assign 5 to oopsGlobal without using the var keyword.

Tests

tests:
  - text: <code>myGlobal</code> should be defined
    testString: assert(typeof myGlobal != "undefined");
  - text: <code>myGlobal</code> should have a value of <code>10</code>
    testString: assert(myGlobal === 10);
  - text: <code>myGlobal</code> should be declared using the <code>var</code> keyword
    testString: assert(/var\s+myGlobal/.test(code));
  - text: <code>oopsGlobal</code> should be a global variable and have a value of <code>5</code>
    testString: assert(typeof oopsGlobal != "undefined" && oopsGlobal === 5);

Challenge Seed

// Declare the myGlobal variable below this line


function fun1() {
  // Assign 5 to oopsGlobal Here

}

// Only change code above this line

function fun2() {
  var output = "";
  if (typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if (typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}

Before Test

var logOutput = "";
var originalConsole = console
function capture() {
    var nativeLog = console.log;
    console.log = function (message) {
        logOutput = message;
        if(nativeLog.apply) {
          nativeLog.apply(originalConsole, arguments);
        } else {
          var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
          nativeLog(nativeMsg);
        }
    };
}

function uncapture() {
  console.log = originalConsole.log;
}
var oopsGlobal;
capture();

After Test

fun1();
fun2();
uncapture();
(function() { return logOutput || "console.log never called"; })();

Solution

var myGlobal = 10;

function fun1() {
  oopsGlobal = 5;
}

function fun2() {
  var output = "";
  if(typeof myGlobal != "undefined") {
    output += "myGlobal: " + myGlobal;
  }
  if(typeof oopsGlobal != "undefined") {
    output += " oopsGlobal: " + oopsGlobal;
  }
  console.log(output);
}