“Remember, null is intended to represent an object that isn’t there.” — Eric Freeman Copy Share Image
“You can extend your object at any time with new properties. To do this you just specify the new property and give… — Eric Freeman Copy Share Image
“methods in objects are properties too. They just happen to have a function assigned to them.” — Eric Freeman Copy Share Image
“If a variable is declared outside a function, it’s GLOBAL. If it’s declared inside a function, it’s LOCAL.” — Eric Freeman Copy Share Image
“When you declare any kind of global variable or define a global function, it is stored as a property in the window… — Eric Freeman Copy Share Image
“We haven’t done much writing code, but we are reading and understanding code, and that can be just as good. So” — Eric Freeman Copy Share Image
“Web Workers have a global function named importScripts that you can use to import one or more JavaScript files into your worker.… — Eric Freeman Copy Share Image
“You’ll also hear developers refer to === (strict equality) as the “identity” operator.” — Eric Freeman Copy Share Image
“An object named arguments is available in every function when that function is called. You” — Eric Freeman Copy Share Image
“Note that the JSON format doesn’t work with methods (so you can’t include, say, a bark method in your JSON string), but… — Eric Freeman Copy Share Image
“A string is always a primitive unless you create it in a special way using an object constructor. We’ll talk about object… — Eric Freeman Copy Share Image
“JavaScript doesn’t have a classical object-oriented model, where you create objects from classes. In fact, JavaScript doesn’t have classes at all. In… — Eric Freeman Copy Share Image
“A callback works like this: give a function to the object that knows about the event. When the event occurs, that object… — Eric Freeman Copy Share Image
“The NoCommand object is an example of a null object. A null object is useful when you don’t have a meaningful object… — Eric Freeman Copy Share Image
“As it turns out, one of the things the new operator does behind the scenes when the object is created is to… — Eric Freeman Copy Share Image
“JavaScript has a very powerful object model, but one that is a bit different than the status quo object-oriented language. Rather than… — Eric Freeman Copy Share Image
“To write code this way, you need to consider the events that can happen, and how your code should react. Computer science… — Eric Freeman Copy Share Image
“What does it mean to assign the value null to a variable? How about “We intend to assign an object to this… — Eric Freeman Copy Share Image
“Window is the global object. It may seem a little weird, but the window object acts as your global environment, so the… — Eric Freeman Copy Share Image
“In fact, there’s a keyword in JavaScript named this, and that is exactly how you tell JavaScript you mean this object we’re… — Eric Freeman Copy Share Image
“That’s because the default prototype for any instance you create (assuming you don’t change it) is Object.” — Eric Freeman Copy Share Image
“Remember what happens when you call getElementById and the id doesn’t exist in the DOM? You get null. Same thing with getAttribute.… — Eric Freeman Copy Share Image
“Lexical scope means that we can determine the scope of a variable by reading our code.” — Eric Freeman Copy Share Image
“using constructors still doesn’t prevent us from changing an object into something else later, because” — Eric Freeman Copy Share Image
“Now when we use the function keyword this way — that is, within a statement, like an assignment statement — we call… — Eric Freeman Copy Share Image
“There are five falsey values in JavaScript: undefined is falsey. null is falsey. 0 is falsey. The empty string is falsey. NaN… — Eric Freeman Copy Share Image
“When you link to multiple JavaScript files from your page, all the global variables are defined in the same global space.” — Eric Freeman Copy Share Image
“Two objects are equal only if the variables containing the object references point to the same object.” — Eric Freeman Copy Share Image
“If you give it an index that is greater than or equal to the length of the string, it returns the empty… — Eric Freeman Copy Share Image
“If you change any property in the prototype, it affects all the objects that inherit from that prototype, unless that object has… — Eric Freeman Copy Share Image
“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… — Eric Freeman Copy Share
“when you assign a value to a variable name that hasn’t been previously declared, it is treated as a new, global variable. So be… — Eric Freeman Copy Share
“Web Workers have a global function named importScripts that you can use to import one or more JavaScript files into your worker. To” — Eric Freeman Copy Share
“If the two values have different types, try to convert them into the same type and then compare them” — Eric Freeman Copy Share
“Well, it’s a browser policy, and it says you can’t retrieve data from a domain that is different from the domain the page itself… — Eric Freeman Copy Share
“Math is not a constructor, or even a function. It’s an object. As you know, Math is a built-in object that you can use… — Eric Freeman Copy Share
“When you pass zero to setTimeout, you’re asking JavaScript to run your timeout handler as soon as it possibly can — and this leads… — Eric Freeman Copy Share
“JavaScript doesn’t have a character type. So characters are returned as new strings containing one character.” — Eric Freeman Copy Share
“Lexical scope means that we can determine the scope of a variable by reading our code.” — Eric Freeman Copy Share
“Q: Q: You said getElementsByTagName returns a list. Do you mean an array? A: A: It returns an object that you can treat like… — Eric Freeman Copy Share
“the truth is JavaScript actually makes two passes over your page: in the first pass it reads all the function definitions, and in the… — Eric Freeman Copy Share
“If you change any property in the prototype, it affects all the objects that inherit from that prototype, unless that object has overridden that… — Eric Freeman Copy Share
“methods in objects are properties too. They just happen to have a function assigned to them.” — Eric Freeman Copy Share
