The reason why outerScopeVar is undefined in all of these examples is because of JavaScript's asynchronous nature. In each case, the code is executing a function that will not immediately return a result. Instead, the function will execute at some point in the future, and the rest of the code will continue to execute in the meantime. In the first example, the img.onload function will set the value of outerScopeVar, but this will not happen until the image has fully loaded. The alert statement is executed before the img.onload function has a chance to run, so it will output undefined. The same thing happens in the second example with setTimeout. The function passed to setTimeout is not executed until the next tick of the event loop, which is after the alert statement has already executed. In the third example, the $.post function is an asynchronous AJAX call. The callback function will be executed when the request has completed, but this will happen sometime after the alert statement has already executed. In the fourth example, the fs.readFile function is also asynchronous. The contents of the file are not available until the function has completed, but again, this happens after the console.log statement has already executed. In the fifth example, the myPromise.then callback function is executed after the promise has been resolved/rejected, but the console.log statement is executed before that happens. The sixth example with observables works the same way as with promises. Finally, the navigator.geolocation.getCurrentPosition function is also asynchronous. The position data is not available until the function has completed, which is after the console.log statement has already executed. To summarize, in all of these examples, the code is attempting to access a variable that has not yet been set because the asynchronous function that sets it has not yet completed.