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4월, 2019의 게시물 표시

6.11 JS Currying and Particials class note and task solving

args.length = a number of args passed by curried function func.legnth = original function's args' number concate next function's argument till it doesn't need any more currring when binded function needs arguments, do not write user.longin(true).bind(user) just like I tried lol but user.login.bind(user, true) //function.bind(context, argument) in that order in number2 way, each function binded are called PARTICIAL functions of user.login

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JS 6.9 task 4 what the fuck is this / Throttle decorator

<HTML> <body> </body> <script> function f(a) { console.log(a) }; // f1000 passes calls to f at maximum once per 1000 ms let f1000 = throttle(f, 1000); function throttle(update, ms){ let isThrottled = false, savedArgs, savedThis; //context can be saved in let function wrapper(){ if(isThrottled) { //if throttled is true, save latest call savedArgs = arguments; savedThis = this; return; } update.apply(this,arguments); //runs and book the next call isThrottled = true; setTimeout(function() { //initiate the flag object and let wrapper runs again isThrottled = false; if(savedArgs) { wrapper.apply(savedThis, savedArgs); //calling the whole function wrapper makes the latest call's infos to be saved savedArgs = savedThis = null; } }, ms); } return wrapper;

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JS 6.9 task3 Debounce decorator

<HTML> <body> </body> <script> let f = debounce(alert, 1000); //setting default value of time function debounce(f, ms) { let isCooldown = false; return function() { if (isCooldown) return; //ignore the call and end the function //if its false, then call the f(=alert) f.apply(this, arguments); isCooldown = true;//flag is on to ignore future calls setTimeout(() => isCooldown = false, ms); //set timeout to turn flag to be false later }; } f(1); // runs immediately f(2); // ignored setTimeout( () => f(3), 100); // ignored ( only 100 ms passed ) setTimeout( () => f(4), 1100); // runs setTimeout( () => f(5), 1500); // ignored (less than 1000 ms from the last run) </script> </HTML>

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JS 6.9 task2 Delaying decorator

<HTML> <body> </body> <script> function f(x) { alert(x); } function delay(func, sec){ return function(){ setTimeout(()=>f.apply(this, arguments), sec); }; //arrow function do not have this, //f.apply takes context and arguments from delay, outter function //that is why filling arguments like setTimeout(fun(args)) //always returned undefined } // create wrappers let f1000 = delay(f, 1000); let f1500 = delay(f, 1500); f1000("test"); // shows "test" after 1000ms f1500("test"); // shows "test" after 1500ms </script> </HTML>

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JS 6.9 task1 Spy decorator

<HTML> <body> </body> <script> function work(a,b){ alert(a + b); } function spy(func){ function wrapper (...args) { //to make parameters to be each array by every call wrapper.calls.push(args); //this is call forwarding : wrapper passes everything it gets //and return back its result return func.apply(this, arguments); //arguments is reserved word, // means all argument the outter object has got }//function definition can be anywhere in the block wrapper.calls = []; //calls is an array return wrapper; } work = spy(work); //now work has the body of wrapper //which has an array calls, and does push everytime it runs work(1, 2); // 3 work(4, 5); // 9 for (let args of work.calls) { alert( 'call:' + args.join() ); // "call:1,2", "call:4,5" } </script> </HTML> <!-- func.call(context, ...args) //spread operater(...) allows to pass ITERABLE (

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JS 6.8 ...

Any setTimeout will run only after the current code has finished......

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JS 6.8 task1 Output every second

<HTML> <body> </body> <script> //inverval way // function printNumbers(from, to){ // let i = from; // let interval = setInterval(function(){ // alert(i); // if(i < to) i++; // 0 ~ 4 // else clearInterval(interval); // },1000); // } //settimeout way, solution, mostly by myself tho function printNumbers(from, to){ let i = from; setTimeout(function run(){ alert(i); if(i < to){ setTimeout(run,1000); } i++; },1000); } printNumbers(0,5); </script>  </HTML>

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