목록js (7)

the murmurous sea

JS ES5: strict / non-strict(sloppy) mode

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode Strict mode JavaScript's strict mode, introduced in ECMAScript 5, is a way to opt in to a restricted variant of JavaScript, thereby implicitly opting-out of "sloppy mode". Strict mode isn't just a subset: it intentionally has different semantics from normal code. Brow developer.mozilla.org https://m.blog.naver.com/on21..
#dev/undone Q 2020. 6. 10. 13:27
JS ES6: Hoisting, Temporal dead zone

The study started from: I can't hoist const function...?! Why...? A. Declaring Variables www.youtube.com/watch?v=dzEieWaOJE0&t=5s www.youtube.com/watch?v=j-9_15QBW2s B. Temporal Dead Zone It's because of : Unlike variables declared with var, which will start with the value undefined, let variables are not initialized until their definition is evaluated. : Accessing the variable before the initia..
#dev/개념정리 2020. 6. 3. 18:20
JS: about Event

What is Event? - The Event interface represents an event which takes place in the DOM. - An event can be triggered by the user action or can also be triggered programmatically. - Event itself contains the properties and methods which are common to all events. - 이벤트는 이벤트 대상, 이벤트 종류, 이벤트가 발생했을 때 실행되는 함수, 이 3가지로 구성 Constructor Event() How to add 1. HTML tag - inline: add the function to the tag pro..
#dev/개념정리 2020. 6. 3. 18:16
JS: EventTarget.addEventListener() (empty)

https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
#dev/개념정리 2020. 6. 3. 13:30
JS ES6: Functions hoisting check

After //1. var console.log('typeof minus:', typeof minus) console.log('minus(5,1):', minus(5,1)) var minus = (a,b) => a - b; //typeof minus: undefined //Uncaught TypeError: minus is not a function at check.js:4 //(anonymous) @ check.js:4 //2. const console.log('typeof minus:', typeof minus) console.log('minus(5,1):', minus(5,1)) const minus = (a,b) => a - b; //Uncaught ReferenceError: Cannot acc..
#dev/개념정리 2020. 6. 3. 11:40
JS: Promise.prototype.then() - incompleted

1. method 2. returns a Promise. 3. As the then and Promise.prototype.catch() methods return promises, they can be chained — an operation called composition. 4. returns a Promise which allows for method chaining. [Syntax] p.then(onFulfilled[, onRejected]); p.then(value => { // fulfillment }, reason => { // rejection }); onFulfilled Optional A Function called if the Promise is fulfilled. : has one..
#dev/개념정리 2020. 5. 21. 21:26
JS: Object.keys() & Object.values() & Object.entries()

Object.keys() 1. method 2. iterated in the same order that a normal loop would. [Syntax] Object.keys(obj) [Return Value] An array : of strings : of a given object's own enumerable property names : that represent all the enumerable properties of the given object. : The ordering of the properties is the same as the obj. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objec..
#dev/개념정리 2020. 5. 12. 17:59
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