๋ฐฐ์ด๊ณผ ๋ฐฐ์ด์ ์ด์ ๋ํด ๊ณต๋ถ.
์ด๊ธฐ์ฝ๋
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Array Cardio ๐ช</title>
</head>
<body>
<p><em>Psst: have a look at the JavaScript Console</em> ๐</p>
<script>
// Get your shorts on - this is an array workout!
// ## Array Cardio Day 1
// Some data we can work with
const inventors = [
{ first: 'Albert', last: 'Einstein', year: 1879, passed: 1955 },
{ first: 'Isaac', last: 'Newton', year: 1643, passed: 1727 },
{ first: 'Galileo', last: 'Galilei', year: 1564, passed: 1642 },
{ first: 'Marie', last: 'Curie', year: 1867, passed: 1934 },
{ first: 'Johannes', last: 'Kepler', year: 1571, passed: 1630 },
{ first: 'Nicolaus', last: 'Copernicus', year: 1473, passed: 1543 },
{ first: 'Max', last: 'Planck', year: 1858, passed: 1947 },
{ first: 'Katherine', last: 'Blodgett', year: 1898, passed: 1979 },
{ first: 'Ada', last: 'Lovelace', year: 1815, passed: 1852 },
{ first: 'Sarah E.', last: 'Goode', year: 1855, passed: 1905 },
{ first: 'Lise', last: 'Meitner', year: 1878, passed: 1968 },
{ first: 'Hanna', last: 'Hammarstrรถm', year: 1829, passed: 1909 }
];
const people = [
'Bernhard, Sandra', 'Bethea, Erin', 'Becker, Carl', 'Bentsen, Lloyd', 'Beckett, Samuel', 'Blake, William', 'Berger, Ric', 'Beddoes, Mick', 'Beethoven, Ludwig',
'Belloc, Hilaire', 'Begin, Menachem', 'Bellow, Saul', 'Benchley, Robert', 'Blair, Robert', 'Benenson, Peter', 'Benjamin, Walter', 'Berlin, Irving',
'Benn, Tony', 'Benson, Leana', 'Bent, Silas', 'Berle, Milton', 'Berry, Halle', 'Biko, Steve', 'Beck, Glenn', 'Bergman, Ingmar', 'Black, Elk', 'Berio, Luciano',
'Berne, Eric', 'Berra, Yogi', 'Berry, Wendell', 'Bevan, Aneurin', 'Ben-Gurion, David', 'Bevel, Ken', 'Biden, Joseph', 'Bennington, Chester', 'Bierce, Ambrose',
'Billings, Josh', 'Birrell, Augustine', 'Blair, Tony', 'Beecher, Henry', 'Biondo, Frank'
];
// Array.prototype.filter()
// 1. Filter the list of inventors for those who were born in the 1500's
// 1. 1500 ๋
๋์ ํ์ด๋ ๋ฐ๋ช
๊ฐ ๋ชฉ๋ก์ ํํฐ๋งํฉ๋๋ค.
// Array.prototype.map()
// 2. Give us an array of the inventors first and last names
// 2.๋ฐ๋ช
๊ฐ์ ์ด๋ฆ๊ณผ ์ฑ์ ๋ฐฐ์ด์ ์ ๊ณตํฉ๋๋ค.
// Array.prototype.sort()
// 3. Sort the inventors by birthdate, oldest to youngest
// 3. ๋ฐ๋ช
๊ฐ๋ฅผ ์๋
์์ผ ์์ผ๋ก ์ ๋ ฌํฉ๋๋ค.
// Array.prototype.reduce()
// 4. How many years did all the inventors live all together?
// 4. ๋ชจ๋ ๋ฐ๋ช
๊ฐ๊ฐ ํจ๊ป ์ด์๋ ์ง ์ผ๋ง๋ ๋์์ต๋๊น?
// 5. Sort the inventors by years lived
// 5. ๋ฐ๋ช
๊ฐ๋ฅผ ์ด์๋ ์ฐ๋๋ณ๋ก ์ ๋ ฌ
// 6. create a list of Boulevards in Paris that contain 'de' anywhere in the name
// https://en.wikipedia.org/wiki/Category:Boulevards_in_Paris
// 6. ์ด๋ฆ์ 'de'๊ฐ ํฌํจ ๋ ํ๋ฆฌ์ Boulevards์ ๋ชฉ๋ก์ ๋ง๋ญ๋๋ค.
// 7. sort Exercise
// Sort the people alphabetically by last name
// 7. ์ฌ๋๋ค์ ์ฑ์ ๊ธฐ์ค์ผ๋ก ์ํ๋ฒณ์์ผ๋ก ์ ๋ ฌ
// 8. Reduce Exercise
// Sum up the instances of each of these
// 8. ์ด๋ค ๊ฐ๊ฐ์ ์ธ์คํด์ค๋ฅผ ์์ฝ
const data = ['car', 'car', 'truck', 'truck', 'bike', 'walk', 'car', 'van', 'bike', 'walk', 'car', 'van', 'car', 'truck' ];
</script>
</body>
</html>
๋์ ๋ ํจ์๋ฅผ ํตํด ๋ฐฐ์ด ๋ด๋ถ๋ฅผ ์ํํ๋ฉด์, ์์๋ง๋ค ์กฐ๊ฑด์ ๋ง์กฑํ๋ ์งํ์ธํจ.
const fifteen = inventors.filter(function(inventor){
if(inventor.year >= 1500 && inventor.year <= 1599){
return true; // keep it!
}else{
return false;
}
});
1๋ฒ๋ฌธ์ ์ธ๋ฐ, ์ด๊ฒฝ์ฐ inventors๋ฐฐ์ด ๋ด๋ถ๋ฅผ ๋๋ฉด์ inventor์ year์ด 1500 ~ 1600์ธ ์์ด๋ค์ ์ฐพ์ ๋ฆฌํดํจ.
๋ฐฐ์ด์ ์์๋ฅผ ์ผ๊ด ๋ณ๊ฒฝํด์ผ ํ๋ ๊ฒฝ์ฐ
callbackํจ์๋ฅผ ์ธ์๋ก ๋ฐ์, callbackํจ์์ return์ผ๋ก ๋ฐํ๋๋ ๊ฐ๋ค์ ์ฌ์กฐํฉํ์ฌ ์๋ก์ด ๋ฐฐ์ด์ ๋ง๋ฌ.
const fullNames = inventors.map(inventor => inventor.first + " " + inventor.last);
inventors๋ฐฐ์ด์ ์๋ก ๋ง๋ค์ด fullNames์ ์ ์ฅ.
๋ฉ์๋ ์ธ์๋ก ๋น๊ตํจ์๋ฅผ ๋์ ํ์ฌ ๋ฐฐ์ด ์์๋ค์ ์ ๋ ฌํฉ๋๋ค.
sort๋ ์๋ก์ด ๋ฐฐ์ด์ ๋ฐํํ์ง์๊ณ ์๋ณธ ๋ฐฐ์ด ์์ฒด๋ฅผ ๋ณ๊ฒฝ์ํค๋๊น ์ฃผ์!
๋ฐฐ์ด.sort(function(a,b)){
return ๋น๊ต๊ฐ;
}
๋น๊ต๊ฐ์ ๋ฐ๋ผ ์์๊ฐ ์ ํด์ง๋๋ค.
๋น๊ต๊ฐ > 0 : a๊ฐ b๋ณด๋ค ์์ ์ซ์์ ์ธ๋ฑ์ค๋ฅผ ๊ฐ์ง๋๋ค.
๋ฐฐ์ด์ ์์ ์ธ๋ฑ์ค๋ผ๋ ๋ป์ ๋ฐฐ์ด์์ ์๋ถ๋ถ์ ์์นํ๋ ๊ฒ์ ์๋ฏธํจ.
์ฆ, a๊ฐ b๋ณด๋ค ์์ ์์นํจ.
๋น๊ต๊ฐ < 0 : b๊ฐ a๋ณด๋ค ์์ ์ซ์์ ์ธ๋ฑ์ค๋ฅผ ๊ฐ์ง๋๋ค. b๊ฐ a๋ณด๋ค ์์ ์์น.
๋น๊ต๊ฐ = 0 : a์ b์ ์์น๋ฅผ ๋ณ๊ฒฝํ์ง ์์.
a-b๊ฐ ์ค๋ฆ์ฐจ์, b-a๊ฐ ๋ด๋ฆผ์ฐจ์
๋ฐฐ์ด์์๋ฅผ ์ํํ๋ฉด์ ์ ์๋ callbackํจ์์ ์ํด ๋จ์ผ ๊ฐ์ผ๋ก ๋์ ์ํฌ ์ ์๋ค.
๋ฐฐ์ด.reduce(๋์ ๋ ๊ฐ, ํ์ฌ ์์ ๊ฐ, ํ์ฌ ์ธ๋ฑ์ค, ์๋ณธ ๋ฐฐ์ด) => {
return ๋์ ๊ฐ์ผ๋ก ๋ณํ๋๋ ๊ฐ
}, ์ด๊ธฐ๊ฐ);
const totalYears = inventors.reduce((total, inventor)=>{
return total + (inventor.passed - inventor.year);
}, 0);
const fifteen = inventors.filter(function(inventor){
if(inventor.year >= 1500 && inventor.year <= 1599){
return true; // keep it!
}else{
return false;
}
});
filter()๋ฅผ ์ด์ฉ ํ์ฌ 1500~1599 ์ฌ์ด์ ๋ฐ๋ช ๊ฐ๋ค์ ํํฐ๋งํจ.
Arrow Function
const fifteen = inventors.filter((inventor=> inventor.year >= 1500 && inventor.year <1600));
ํ์ดํํจ์๋ฅผ ์ด์ฉํด ํ์ค๋ก ์ค์ผ ์ ์๋ค.
๊ฒฐ๊ณผ
const fullNames = inventors.map(inventor => inventor.first + " " + inventor.last);
map์ ์ด์ฉํ์ฌ ๋ณด์ฌ์ค ์ ์๋ค.
ํ์ํ ๋ ๋ฐฑํฑ(`)์ ์ด์ฉํด ์ค๊ฐ์ " " ๋ถ๋ถ์์ด ํ๋ฒ์ ์ถ๋ ฅํ ์ ์๋ค.
const fullNames = inventors.map(inventor => `${inventor.first} ${inventor.last}`);
const ordered = inventors.sort(function(a, b){
if(a.year > a.year){
return 1;
}else{
return -1;
}
})
sort๋ฅผ ์ด์ฉํ์ฌ ์ ๋ ฌ ํ ์ ์๋ค.
Arrow Function
const ordered = inventors.sort((a,b)=>a.year>b.year ? 1 : -1);
๊ฒฐ๊ณผ
var totalYears = 0;
for(var i=0;i<inventors.length; i++){
totalYears += inventors[i].year
}
๋ฐ๋ณต๋ฌธ ๋๋ ค์ ์ถ๋ ฅํ ์๋ ์์ง๋ง, reduce๋ฅผ ์ด์ฉํ ์ ์๋ค.
reduce
const totalYears = inventors.reduce((total, inventor)=>{
return total + (inventor.passed - inventor.year);
}, 0);
const oldest = inventors.sort(function(a,b){
const lastGuy = a.passed - a.year;
const nextGuy = b.passed - b.year;
// if(lastGuy > nextGuy){
// return -1;
// }else{
// return 1;
// }
return lastGuy > nextGuy ? -1 : 1; })
sort๋ฅผ ์ด์ฉํด ์ ๋ ฌํ๋๋ฐ,
์ฃผ์ ์ฒ๋ฆฌ๋ ๋ถ๋ถ์ 3ํญ์ฐ์ฐ์๋ฅผ ์ด์ฉํ์ฌ return ๋ถ๋ถ์ฒ๋ผ ์ธ ์ ์๋ค.
const category = document.querySelector('.mw-category');
const links = Array.from(category.querySelectorAll('a'));
const de = links
.map(link =>link.textContent)
.filter(streetName => streetName.includes('de'));
const alpha = people.sort(function(lastOne, nextOne){
const [aLast, aFirst] = lastOne.split(', ');
const [bLast, bFirst] = nextOne.split(', ');
return aLast > bLast ? 1 : -1; });
lastOne๊ณผ nextOne์์ split์ ์ด์ฉํ์ฌ ,๋ฅผ ๊ธฐ์ค์ผ๋ก ๋๋๋ค.
[last, Frist]
๊ทธ ํ ์ ๋ ฌํจ.
const data = ['car', 'car', 'truck', 'truck', 'bike', 'walk', 'car', 'van', 'bike', 'walk', 'car', 'van', 'car', 'truck' ];
const transportation = data.reduce(function(obj, item){
// console.log(item);
if(!obj[item]){
obj[item] = 0;
}
obj[item]++;
return obj;
},{});
obj[item]์ด ๋น๊ฐ์ด๋ฉด 0, ์๋๋ฉด item์ ๊ฐ์ 1์ฆ๊ฐ.
item์ด ํค๊ฐ์ด๋๋ค.
{car: 5, truck: 3, bike: 2, walk: 2, van: 2}bike: 2car: 5truck: 3van: 2walk: 2