Head First JavaScript Programming Quotes

“an important thing to know about JavaScript: there’s one queue and one “thread of control,” meaning there is only one of me going through the events one at a time.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Joe: What’s the target? Judy: Like I said, it’s the element that generated the event. Like if you click on a specific image, the target will be that image.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Q: Q: You said getElementsByTagName returns a list. Do you mean an array? A: A: It returns an object that you can treat like an array, but it’s actually an object called a NodeList. A NodeList is a collection of Nodes, which is just a technical name for the element objects that you see in the DOM tree. You”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“To write code this way, you need to consider the events that can happen, and how your code should react. Computer science types like to say that this kind of code is asynchronous, because we’re writing code to be invoked later, if and when an event occurs. This”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“The responsibility of the model is to store the state of the game and implement logic that modifies that state.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“repetition is what really drives the learning home!”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“As of HTML5, you are allowed to use all numbers as an element id. As”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“position: absolute” positions an element based on the position of its most closely positioned parent.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Two objects are equal only if the variables containing the object references point to the same object.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“NaN never equals any other value, including itself, so to test for NaN use the function isNaN.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“If I had a dime for every time I’ve heard that one”, thought Larry, knowing that spec-change-no-problem was a fantasy. “And”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“JavaScript doesn’t have a character type. So characters are returned as new strings containing one character.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“If you give it an index that is greater than or equal to the length of the string, it returns the empty string.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“A string is always a primitive unless you create it in a special way using an object constructor. We’ll talk about object constructors later. And you can always use the typeof operator on your variable to see if it is of type string or object.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“There are five falsey values in JavaScript: undefined is falsey. null is falsey. 0 is falsey. The empty string is falsey. NaN is falsey.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“concentrate on knowing what is falsey, and then everything else you can consider truthy. Let’s look at some examples of using these falsey values”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Two references are equal only if they reference the same object”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“You’ll also hear developers refer to === (strict equality) as the “identity” operator.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“If the two values have different types, try to convert them into the same type and then compare them”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“NaN isn’t equal to anything, not even itself, so,”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Remember, null is intended to represent an object that isn’t there.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“What does it mean to assign the value null to a variable? How about “We intend to assign an object to this variable at some point, but we haven’t yet.” Now, if you’re scratching your head and saying “Hmm, why didn’t they just use undefined for that?” then you’re in good company. The answer comes from the very beginnings of JavaScript. The idea was to have one value for variables that haven’t been initialized to anything yet, and another that means the lack of an object. It isn’t pretty, and it’s a little redundant, but it is what it is at this point. Just”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“The type of undefined is undefined. Why?”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Remember what happens when you call getElementById and the id doesn’t exist in the DOM? You get null. Same thing with getAttribute. If”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“A callback works like this: give a function to the object that knows about the event. When the event occurs, that object will call you back, or notify you, by calling that function. You’re going to see this pattern in JavaScript for a variety of events.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“In fact, there’s a keyword in JavaScript named this, and that is exactly how you tell JavaScript you mean this object we’re in.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“Using a method to change a property is another example of encapsulation whereby we can often improve the maintainability and extensibility of code by letting an object worry about how it gets things done. It’s”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“When you delete a property, you’re not just deleting the value of the property, you’re deleting the property itself. And, if you try to use fido.dogYears after deleting it, it will evaluate to undefined.”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“You can extend your object at any time with new properties. To do this you just specify the new property and give it a value. For”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide

“the truth is JavaScript actually makes two passes over your page: in the first pass it reads all the function definitions, and in the second it begins executing your code. So,”
― Eric Freeman, Head First JavaScript Programming: A Brain-Friendly Guide