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Stack #2807592
Question | Answer |
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User Interface (UI) | The "User Interface" or UI of an app refers to how a person (user) interacts with the computer or app. |
UI Elements | objects, like buttons, images, text boxes, pull down menus, screens and so on. |
UI Events | controls, like click, scroll, move mouse, type keyboard key, etc. |
Event-driven program | a program designed to run blocks of code or functions in response to specified events (e.g. a mouse click) |
Event handling | an overarching term for the coding tasks involved in making your app respond to events by triggering functions. |
Event listener | a command (onEvent in App Lab) that can be set up to trigger a function when a particular type of event occurs on a particular UI element. |
Callback function | a function specified as part of an event listener; it is written by the programmer but called by the system as the result of an event trigger. |
Debugging | Finding and fixing problems in your code or algorithm |
Variable | In JavaScript (and most programming languages) the most primitive type of memory you can use is called a variable. It's called a variable because it's a piece of memory in which you can change what's stored - its value can vary. |
Expression | Any valid unit of code that resolves to a single value. (Variables can be assigned values that are the result of an expression.) |
Data Type | All values in a programming language have a "type" - such as a Number, Boolean, or String - that dictates how the computer will interpret it. For example 7+5 is interpreted differently from "7"+"5" |
Variable Scope | dictates what portions of the code can "see" or use a variable, typically derived from where the variable was first created. |
String | Any sequence of characters between quotation marks (ex: "hello", "42", "this is a string!"). |
Concatenate | to link together or join. Typically used when joining together text Strings in programming (e.g. "Hello, "+name) |
if Statement | The common programming structure that implements "conditional statements". |
Conditionals | Another term for if statements -- statements that only run under certain conditions |
Selection | A generic term for a type of programming statement (usually an if-statement) that uses a Boolean condition to determine, or select, whether or not to run a certain block of statements. Resources |
Boolean | A single value of either TRUE or FALSE |
Boolean Expression | in programming, an expression that evaluates to True or False. |
while loop | a programming construct used to repeat a set of commands while a boolean condition is true. |
Models and Simulations | a program which replicates or mimics key features of a real world event in order to investigate its behavior without the cost, time, or danger of running an experiment in real life |
List | A generic term for a programming data structure that holds multiple items. |
Array | A data structure in JavaScript used to represent a list. |
Key event | an event triggered by pressing or releasing a key on the keyboard. |
keyup | event type triggered when key is released on the keyboard |
keydown | event type triggered when key is pressed down on the keyboard |
event.key | Use event.key - from the event parameter of the onEvent callback function - to figure out which key was pressed. |
for loop | A typical looping construct designed to make it easy to repeat a section of code using a counter variable. The for loop combines the creation of a variable, a boolean looping condition, and an update to the variable in one statement. |
return | a command used to end execution of a function and resume execution at the point where the function was called. |
Canvas | a user interface element to use in HTML/JavaScript which acts as a digital canvas, allowing the programmatic drawing and manipulation of pixels, basic shapes, figures and images. |