Add arrayToCSV

snippets/arrayToCSV.md

@@ -0,0 +1,16 @@
+### arrayToCSV
+
+Converts a 2D array to a comma-separated values (CSV) string.
+
+Use `Array.map()` and `String.join(delimiter)` to combine individual 1D arrays (rows) into strings.
+Use `String.join('\n')` to combine all rows into a CSV string, separating each row with a newline.
+Omit the second argument, `delimiter` to use a default delimiter of `,`.
+
+```js
+const arrayToCSV = (arr, delimiter = ',') => arr.map(v => v.join(delimiter)).join('\n');
+```
+
+```js
+arrayToCSV([['a','b'],['c','d']]); // 'a,b\nc,d'
+arrayToCSV([['a','b'],['c','d']], ';'); // 'a;b\nc;d'
+```

tag_database

@@ -1,6 +1,7 @@
 all:array,function
 any:array,function
 approximatelyEqual:math
+arrayToCSV:array,string,utility
 arrayToHtmlList:browser,array
 ary:adapter,function
 atob:node,string,utility

test/arrayToCSV/arrayToCSV.js

@@ -0,0 +1,2 @@
+const arrayToCSV = (arr, delimiter = ',') => arr.map(v => v.join(delimiter)).join('\n');
+module.exports = arrayToCSV;

test/arrayToCSV/arrayToCSV.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const arrayToCSV = require('./arrayToCSV.js');
+
+test('arrayToCSV is a Function', () => {
+  expect(arrayToCSV).toBeInstanceOf(Function);
+});
+test('arrayToCSV works with default delimiter', () => {
+  expect(arrayToCSV([['a','b'],['c','d']])).toBe('a,b\nc,d');
+});
+test('arrayToCSV works with custom delimiter', () => {
+  expect(arrayToCSV([['a','b'],['c','d']], ';')).toBe('a;b\nc;d');
+});

test/elo/elo.js

@@ -5,13 +5,12 @@ const newRating = (rating, i) =>
 (selfRating || rating) + kFactor * (i - expectedScore(i ? a : b, i ? b : a));
 if (ratings.length === 2) {
 return [newRating(a, 1), newRating(b, 0)];
-} else {
-for (let i = 0; i < ratings.length; i++) {
-let j = i;
-while (j < ratings.length - 1) {
-[ratings[i], ratings[j + 1]] = elo([ratings[i], ratings[j + 1]], kFactor);
-j++;
 }
+for (let i = 0, len = ratings.length; i < len; i++) {
+let j = i;
+while (j < len - 1) {
+j++;
+[ratings[i], ratings[j]] = elo([ratings[i], ratings[j]], kFactor);
 }
 }
 return ratings;

test/equals/equals.js

@@ -1,7 +1,7 @@
 const equals = (a, b) => {
 if (a === b) return true;
 if (a instanceof Date && b instanceof Date) return a.getTime() === b.getTime();
-if (!a || !b || (typeof a != 'object' && typeof b !== 'object')) return a === b;
+if (!a || !b || (typeof a !== 'object' && typeof b !== 'object')) return a === b;
 if (a === null || a === undefined || b === null || b === undefined) return false;
 if (a.prototype !== b.prototype) return false;
 let keys = Object.keys(a);