Add JSONtoCSV

Resolve #686

snippets/JSONtoCSV.md

@@ -0,0 +1,26 @@
+### JSONtoCSV
+
+Converts an array of objects to a comma-separated values (CSV) string that contains only the `columns` specified.
+
+Use `Array.join(demiliter)` to combine all the names in `columns` to create the first row.
+Use `Array.map()` and `Array.reduce()` to create a row for each object, substituting non-existent values with empty strings and only mapping values in `columns`.
+Use `Array.join('\n')` to combine all rows into a string.
+Omit the third argument, `delimiter`, to use a default delimiter of `,`.
+
+```js
+const JSONtoCSV = (arr, columns, delimiter = ',') =>
+  [
+    columns.join(delimiter),
+    ...arr.map(obj =>
+      columns.reduce(
+        (acc, key) => `${acc}${!acc.length ? '' : delimiter}"${!obj[key] ? '' : obj[key]}"`,
+        ''
+      )
+    )
+  ].join('\n');
+```
+
+```js
+JSONtoCSV([{ a: 1, b: 2 }, { a: 3, b: 4, c: 5 }, { a: 6 }, { b: 7 }], ['a', 'b']); // 'a,b\n"1","2"\n"3","4"\n"6",""\n"","7"'
+JSONtoCSV([{ a: 1, b: 2 }, { a: 3, b: 4, c: 5 }, { a: 6 }, { b: 7 }], ['a', 'b'], ';'); // 'a;b\n"1";"2"\n"3";"4"\n"6";""\n"";"7"'
+```

snippets/arrayToCSV.md

@@ -2,8 +2,8 @@
 
 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.
+Use `Array.map()` and `Array.join(delimiter)` to combine individual 1D arrays (rows) into strings.
+Use `Array.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

tag_database

@@ -152,6 +152,7 @@ isUndefined:type
 isUpperCase:string,utility
 isValidJSON:type,json
 join:array
+JSONtoCSV:array,string,object,advanced
 JSONToFile:node,json
 last:array
 lcm:math,recursion

test/JSONtoCSV/JSONtoCSV.js

@@ -0,0 +1,11 @@
+const JSONtoCSV = (arr, columns, delimiter = ',') =>
+[
+columns.join(delimiter),
+...arr.map(obj =>
+columns.reduce(
+(acc, key) => `${acc}${!acc.length ? '' : delimiter}"${!obj[key] ? '' : obj[key]}"`,
+''
+)
+)
+].join('\n');
+module.exports = JSONtoCSV;

test/JSONtoCSV/JSONtoCSV.test.js

@@ -0,0 +1,12 @@
+const expect = require('expect');
+const JSONtoCSV = require('./JSONtoCSV.js');
+
+test('JSONtoCSV is a Function', () => {
+  expect(JSONtoCSV).toBeInstanceOf(Function);
+});
+test('JSONtoCSV works with default delimiter', () => {
+  expect(JSONtoCSV([{ a: 1, b: 2 }, { a: 3, b: 4, c: 5 }, { a: 6 }, { b: 7 }], ['a', 'b'])).toBe('a,b\n"1","2"\n"3","4"\n"6",""\n"","7"');
+});
+test('JSONtoCSV works with custom delimiter', () => {
+  expect(JSONtoCSV([{ a: 1, b: 2 }, { a: 3, b: 4, c: 5 }, { a: 6 }, { b: 7 }], ['a', 'b'], ';')).toBe('a;b\n"1";"2"\n"3";"4"\n"6";""\n"";"7"');
+});