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JavaScript - Q1

memorize.ai (lvl 286)

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setInterval()

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JavaScript Web Dev

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6 years ago

Date created

Mar 1, 2020

Cards (14)

Section 1

(14 cards)

setInterval()

Front

- calls a function at specified intervals - continue call the function until clearInterval() is called

Back

null

Front

- no value - non-exist value

Back

pass by value

Front

- string, number, boolean - primitive type are passed by value

Back

querySelectorAll()

Front

returns a static (not live) NodeList of matching elements

Back

hoisting

Front

- variable declarations are processed prior than other code - no matter where they are

Back

data type

Front

- boolean, string, number - undefined, null - object, symbol

Back

querySelector()

Front

returns the first Element within the document that matches the specified selector

Back

how THIS bound ?

Front

When 'THIS' is inside of an object's method — the function's owner is the object. Thus the 'this' keyword is bound to the object. Yet when it is inside of a function, either stand alone or within another method, it will always refer to the window/global object

Back

how THIS bound in arrow function

Front

Arrow Functions lexically bind their context - so this actually refers to the originating context - more intuitive

Back

RegExp.test()

Front

- takes a string, checks it against the regex - return true if match

Back

Manipulate DOM with JS

Front

- getElements ByID, ByClassname, ByTagName - querySelector()

Back

remove element from array

Front

- use splice(), not delete - delete() will replace value with undefined

Back

pass by reference

Front

- object, array passed by reference

Back

undefined

Front

- value not yet defined - typeof undefined === undefined

Back