From 7f532a074d6fb774ece27aca12afff4c9a9326ab Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Fri, 26 Jan 2018 13:48:50 +0200
Subject: [PATCH] Add pullBy

---
 snippets/pullBy.md | 25 +++++++++++++++++++++++++
 tag_database       |  3 ++-
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 snippets/pullBy.md

diff --git a/snippets/pullBy.md b/snippets/pullBy.md
new file mode 100644
index 000000000..b8d523a39
--- /dev/null
+++ b/snippets/pullBy.md
@@ -0,0 +1,25 @@
+### pullBy
+
+Mutates the original array to filter out the values specified, based on a given iterator function.
+
+Check if the last argument provided in a function.
+Use `Array.map()` to apply the iterator function `fn` to all array elements.
+Use `Array.filter()` and `Array.includes()` to pull out the values that are not needed.
+Use `Array.length = 0` to mutate the passed in an array by resetting it's length to zero and `Array.push()` to re-populate it with only the pulled values.
+
+```js
+const pullBy = (arr, ...args) => {
+  const length = args.length;
+  let fn = length > 1 ? args[length - 1] : undefined;
+  fn = typeof fn == 'function' ? (args.pop(), fn) : undefined;
+  let argState = (Array.isArray(args[0]) ? args[0] : args).map(val => fn(val));
+  let pulled = arr.filter((v, i) => !argState.includes(fn(v)));
+  arr.length = 0;
+  pulled.forEach(v => arr.push(v));
+};
+```
+
+```js
+var myArray = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];
+pullBy(myArray, [{ 'x': 1 }, { 'x': 3 }], o => o.x); // myArray = [{ x: 2 }]
+```
diff --git a/tag_database b/tag_database
index 2ddb8058d..34456499e 100644
--- a/tag_database
+++ b/tag_database
@@ -177,6 +177,7 @@ promisify:adapter,function,promise
 pull:array
 pullAtIndex:array
 pullAtValue:array
+pullBy:array,function,advanced
 randomHexColorCode:utility,random
 randomIntArrayInRange:math,utility,random
 randomIntegerInRange:math,utility,random
@@ -256,4 +257,4 @@ xProd:array,math
 yesNo:utility,regexp
 zip:array
 zipObject:array,object
-zipWith:array,advanced
+zipWith:array,function,advanced