Merge pull request #757 from 30-seconds/date-snippets

[FEATURE] Date snippets

snippets/compose.md

@@ -12,9 +12,6 @@ const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));
 ```js
 const add5 = x => x + 5;
 const multiply = (x, y) => x * y;
-const multiplyAndAdd5 = compose(
-  add5,
-  multiply
-);
+const multiplyAndAdd5 = compose(add5, multiply);
 multiplyAndAdd5(5, 2); // 15
 ```

snippets/dayOfYear.md

@@ -0,0 +1,15 @@
+### dayOfYear
+
+Gets the day of the year from a `Date` object.
+
+Use `new Date()` and `Date.prototype.getFullYear()` to get the first day of the year as a `Date` object, subtract it from the provided `date` and divide with the milliseconds in each day to get the result.
+Use `Math.floor()` to appropriately round the resulting day count to an integer.
+
+```js
+const dayOfYear = date =>
+  Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);
+```
+
+```js
+dayOfYear(new Date()); // 272
+```

snippets/degreesToRads.md

@@ -5,7 +5,7 @@ Converts an angle from degrees to radians.
 Use `Math.PI` and the degree to radian formula to convert the angle from degrees to radians.
 
 ```js
-const degreesToRads = deg => (deg * Math.PI) / 180.0;
+const degreesToRads = deg => deg * Math.PI / 180.0;
 ```
 
 ```js

snippets/getMeridiemSuffixOfInteger.md

@@ -11,8 +11,8 @@ const getMeridiemSuffixOfInteger = num =>
     : num === 12
       ? 12 + 'pm'
       : num < 12
-        ? (num % 12) + 'am'
-        : (num % 12) + 'pm';
+        ? num % 12 + 'am'
+        : num % 12 + 'pm';
 ```
 
 ```js

snippets/hz.md

@@ -11,7 +11,7 @@ Omit the second argument, `iterations`, to use the default of 100 iterations.
 const hz = (fn, iterations = 100) => {
   const before = performance.now();
   for (let i = 0; i < iterations; i++) fn();
-  return (1000 * iterations) / (performance.now() - before);
+  return 1000 * iterations / (performance.now() - before);
 };
 ```
 

snippets/isAfterDate.md

@@ -0,0 +1,13 @@
+### isAfterDate
+
+Check if a date is after another date.
+
+Use the greater than operator (`>`) to check if the first date comes after the second one.
+
+```js
+const isAfterDate = (dateA, dateB) => dateA > dateB;
+```
+
+```js
+isAfterDate(new Date(2010, 10, 21), new Date(2010, 10, 20)); // true
+```

snippets/isBeforeDate.md

@@ -0,0 +1,13 @@
+### isBeforeDate
+
+Check if a date is before another date.
+
+Use the less than operator (`<`) to check if the first date comes before the second one.
+
+```js
+const isBeforeDate = (dateA, dateB) => dateA < dateB;
+```
+
+```js
+isBeforeDate(new Date(2010, 10, 20), new Date(2010, 10, 21)); // true
+```

snippets/isSameDate.md

@@ -0,0 +1,13 @@
+### isSameDate
+
+Check if a date is the same as another date.
+
+Use `Date.prototype.toISOString()` and strict equality checking (`===`) to check if the first date is the same as the second one.
+
+```js
+const isSameDate = (dateA, dateB) => dateA.toISOString() === dateB.toISOString();
+```
+
+```js
+isSameDate(new Date(2010, 10, 20), new Date(2010, 10, 20)); // true
+```

snippets/lcm.md

@@ -8,7 +8,7 @@ The GCD formula uses recursion.
 ```js
 const lcm = (...arr) => {
   const gcd = (x, y) => (!y ? x : gcd(y, x % y));
-  const _lcm = (x, y) => (x * y) / gcd(x, y);
+  const _lcm = (x, y) => x * y / gcd(x, y);
   return [...arr].reduce((a, b) => _lcm(a, b));
 };
 ```

snippets/luhnCheck.md

@@ -15,7 +15,7 @@ const luhnCheck = num => {
     .reverse()
     .map(x => parseInt(x));
   let lastDigit = arr.splice(0, 1)[0];
-  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val * 2) % 9) || 9), 0);
+  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + (val * 2) % 9 || 9), 0);
   sum += lastDigit;
   return sum % 10 === 0;
 };

snippets/maxDate.md

@@ -0,0 +1,19 @@
+### maxDate
+
+Returns the maximum of the given dates.
+
+Use `Math.max.apply()` to find the maximum date value, `new Date()` to convert it to a `Date` object.
+
+```js
+const maxDate = (...dates) => new Date(Math.max.apply(null, ...dates));
+```
+
+```js
+const array = [
+  new Date(2017, 4, 13),
+  new Date(2018, 2, 12),
+  new Date(2016, 0, 10),
+  new Date(2016, 0, 9)
+];
+maxDate(array); // 2018-03-11T22:00:00.000Z
+```

snippets/minDate.md

@@ -0,0 +1,19 @@
+### minDate
+
+Returns the minimum of the given dates.
+
+Use `Math.min.apply()` to find the minimum date value, `new Date()` to convert it to a `Date` object.
+
+```js
+const minDate = (...dates) => new Date(Math.min.apply(null, ...dates));
+```
+
+```js
+const array = [
+  new Date(2017, 4, 13),
+  new Date(2018, 2, 12),
+  new Date(2016, 0, 10),
+  new Date(2016, 0, 9)
+];
+minDate(array); // 2016-01-08T22:00:00.000Z
+```

snippets/percentile.md

@@ -6,7 +6,7 @@ Use `Array.prototype.reduce()` to calculate how many numbers are below the value
 
 ```js
 const percentile = (arr, val) =>
-  (100 * arr.reduce((acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0), 0)) / arr.length;
+  100 * arr.reduce((acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0), 0) / arr.length;
 ```
 
 ```js

snippets/radsToDegrees.md

@@ -5,7 +5,7 @@ Converts an angle from radians to degrees.
 Use `Math.PI` and the radian to degree formula to convert the angle from radians to degrees.
 
 ```js
-const radsToDegrees = rad => (rad * 180.0) / Math.PI;
+const radsToDegrees = rad => rad * 180.0 / Math.PI;
 ```
 
 ```js

tag_database

@@ -44,6 +44,7 @@ CSVToArray:string,array,utility,intermediate
 CSVToJSON:string,array,object,advanced
 currentURL:browser,url,beginner
 curry:function,recursion,intermediate
+dayOfYear:date,beginner
 debounce:function,intermediate
 decapitalize:string,array,intermediate
 deepClone:object,recursion,intermediate
@@ -130,8 +131,10 @@ intersectionWith:array,function,intermediate
 invertKeyValues:object,function,intermediate
 is:type,array,regexp,beginner
 isAbsoluteURL:string,utility,browser,url,intermediate
+isAfterDate:date,utility,beginner
 isAnagram:string,regexp,intermediate
 isArrayLike:type,array,intermediate
+isBeforeDate:date,utility,beginner
 isBoolean:type,beginner
 isBrowser:utility,browser,intermediate
 isBrowserTabFocused:browser,beginner
@@ -149,6 +152,7 @@ isPlainObject:type,object,intermediate
 isPrime:math,beginner,intermediate
 isPrimitive:type,function,array,string,intermediate
 isPromiseLike:type,function,promise,intermediate
+isSameDate:date,utility,beginner
 isSorted:array,intermediate
 isString:type,string,beginner
 isSymbol:type,beginner
@@ -172,11 +176,13 @@ mask:string,utility,regexp,intermediate
 matches:object,type,intermediate
 matchesWith:object,type,function,intermediate
 maxBy:math,array,function,beginner
+maxDate:date,math,beginner
 maxN:array,math,beginner
 median:math,array,intermediate
 memoize:function,advanced
 merge:object,array,intermediate
 minBy:math,array,function,beginner
+minDate:date,math,beginner
 minN:array,math,beginner
 mostPerformant:utility,function
 negate:function,beginner

test/dayOfYear/dayOfYear.js

@@ -0,0 +1,3 @@
+const dayOfYear = date =>
+  Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);
+module.exports = dayOfYear;

test/dayOfYear/dayOfYear.test.js

@@ -0,0 +1,6 @@
+const expect = require('expect');
+const dayOfYear = require('./dayOfYear.js');
+
+test('dayOfYear is a Function', () => {
+  expect(dayOfYear).toBeInstanceOf(Function);
+});

test/degreesToRads/degreesToRads.js

@@ -1,2 +1,2 @@
-const degreesToRads = deg => (deg * Math.PI) / 180.0;
+const degreesToRads = deg => deg * Math.PI / 180.0;
 module.exports = degreesToRads;

test/getMeridiemSuffixOfInteger/getMeridiemSuffixOfInteger.js

@@ -4,6 +4,6 @@ const getMeridiemSuffixOfInteger = num =>
     : num === 12
       ? 12 + 'pm'
       : num < 12
-        ? (num % 12) + 'am'
-        : (num % 12) + 'pm';
+        ? num % 12 + 'am'
+        : num % 12 + 'pm';
 module.exports = getMeridiemSuffixOfInteger;

test/hz/hz.js

@@ -1,6 +1,6 @@
 const hz = (fn, iterations = 100) => {
   const before = performance.now();
   for (let i = 0; i < iterations; i++) fn();
-  return (1000 * iterations) / (performance.now() - before);
+  return 1000 * iterations / (performance.now() - before);
 };
 module.exports = hz;

test/isAfterDate/isAfterDate.js

@@ -0,0 +1,2 @@
+const isAfterDate = (dateA, dateB) => dateA > dateB;
+module.exports = isAfterDate;

test/isAfterDate/isAfterDate.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const isAfterDate = require('./isAfterDate.js');
+
+test('isAfterDate is a Function', () => {
+  expect(isAfterDate).toBeInstanceOf(Function);
+});
+test('isAfterDate produces the correct result', () => {
+  expect(isAfterDate(new Date(2010, 10, 21), new Date(2010, 10, 20))).toBeTruthy();
+});
+test('isBeforeDate produces the correct result', () => {
+  expect(isAfterDate(new Date(2010, 10, 20), new Date(2010, 10, 21))).toBeFalsy();
+});

test/isBeforeDate/isBeforeDate.js

@@ -0,0 +1,2 @@
+const isBeforeDate = (dateA, dateB) => dateA < dateB;
+module.exports = isBeforeDate;

test/isBeforeDate/isBeforeDate.test.js

@@ -0,0 +1,13 @@
+const expect = require('expect');
+const isBeforeDate = require('./isBeforeDate.js');
+
+test('isBeforeDate is a Function', () => {
+  expect(isBeforeDate).toBeInstanceOf(Function);
+});
+test('isBeforeDate produces the correct result', () => {
+  expect(isBeforeDate(new Date(2010, 10, 20), new Date(2010, 10, 21))).toBeTruthy();
+});
+test('isBeforeDate produces the correct result', () => {
+  expect(isBeforeDate(new Date(2010, 10, 21), new Date(2010, 10, 20))).toBeFalsy();
+});
+

test/isSameDate/isSameDate.js

@@ -0,0 +1,2 @@
+const isSameDate = (dateA, dateB) => dateA.toISOString() === dateB.toISOString();
+module.exports = isSameDate;

test/isSameDate/isSameDate.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const isSameDate = require('./isSameDate.js');
+
+test('isSameDate is a Function', () => {
+  expect(isSameDate).toBeInstanceOf(Function);
+});
+test('isSameDate produces the correct result', () => {
+  expect(isSameDate(new Date(2010, 10, 20), new Date(2010, 10, 20))).toBeTruthy();
+});
+test('isSameDate produces the correct result', () => {
+  expect(isSameDate(new Date(2010, 10, 20), new Date(2010, 10, 21))).toBeFalsy();
+});

test/lcm/lcm.js

@@ -1,6 +1,6 @@
 const lcm = (...arr) => {
   const gcd = (x, y) => (!y ? x : gcd(y, x % y));
-  const _lcm = (x, y) => (x * y) / gcd(x, y);
+  const _lcm = (x, y) => x * y / gcd(x, y);
   return [...arr].reduce((a, b) => _lcm(a, b));
 };
 module.exports = lcm;

test/luhnCheck/luhnCheck.js

@@ -4,7 +4,7 @@ const luhnCheck = num => {
     .reverse()
     .map(x => parseInt(x));
   let lastDigit = arr.splice(0, 1)[0];
-  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val * 2) % 9) || 9), 0);
+  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + (val * 2) % 9 || 9), 0);
   sum += lastDigit;
   return sum % 10 === 0;
 };

test/maxDate/maxDate.js

@@ -0,0 +1,2 @@
+const maxDate = (...dates) => new Date(Math.max.apply(null, ...dates));
+module.exports = maxDate;

test/maxDate/maxDate.test.js

@@ -0,0 +1,15 @@
+const expect = require('expect');
+const maxDate = require('./maxDate.js');
+
+test('maxDate is a Function', () => {
+  expect(maxDate).toBeInstanceOf(Function);
+});
+test('maxDate produces the maximum date', () => {
+  const array = [
+    new Date(2017, 4, 13),
+    new Date(2018, 2, 12),
+    new Date(2016, 0, 10),
+    new Date(2016, 0, 9)
+  ];
+  expect(maxDate(array)).toEqual(new Date(2018, 2, 12));
+});

test/minDate/minDate.js

@@ -0,0 +1,2 @@
+const minDate = (...dates) => new Date(Math.min.apply(null, ...dates));
+module.exports = minDate;

test/minDate/minDate.test.js

@@ -0,0 +1,15 @@
+const expect = require('expect');
+const minDate = require('./minDate.js');
+
+test('minDate is a Function', () => {
+  expect(minDate).toBeInstanceOf(Function);
+});
+test('minDate produces the maximum date', () => {
+  const array = [
+    new Date(2017, 4, 13),
+    new Date(2018, 2, 12),
+    new Date(2016, 0, 10),
+    new Date(2016, 0, 9)
+  ];
+  expect(minDate(array)).toEqual(new Date(2016, 0, 9));
+});

test/percentile/percentile.js

@@ -1,3 +1,3 @@
 const percentile = (arr, val) =>
-  (100 * arr.reduce((acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0), 0)) / arr.length;
+  100 * arr.reduce((acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0), 0) / arr.length;
 module.exports = percentile;

test/radsToDegrees/radsToDegrees.js

@@ -1,2 +1,2 @@
-const radsToDegrees = rad => (rad * 180.0) / Math.PI;
+const radsToDegrees = rad => rad * 180.0 / Math.PI;
 module.exports = radsToDegrees;