Add Immutable Remove With The Spread Operator as a javascript til

javascript/immutable-remove-with-the-spread-operator.md

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+# Immutable Remove With The Spread Operator
+
+ES6 introduces the [spread
+operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator)
+which allows you to expand arrays in place for function calls, array
+composition, array destructuring, etc. One thing the spread operator allows
+you to concisely do with array composition is perform immutable operations
+on arrays. For instance, to remove an item from an array by index, you can
+throw together the following function.
+
+```javascript
+const remove = (items,index) => {
+  return [...items.slice(0,index),
+          ...items.slice(index+1,items.length)];
+};
+
+const list = [1,2,3,4,5];
+remove(list, 2);
+// [1,2,3,4]
+list
+// [1,2,3,4,5]
+```
+
+It only took a couple lines of code and immutability is baked in.