feat: Add needed utilities from Bootsrap-Vue library.

Author: woothu

src/utils/array.js

@@ -2,3 +2,4 @@ export const arrayIncludes = (array, value) => array.indexOf(value) !== -1
 export function concat () {
   return Array.prototype.concat.apply([], arguments)
 }
+export const isArray = Array.isArray

src/utils/dom.js

@@ -0,0 +1,11 @@
+export const addClass = (el, className) => {
+  if (className && isElement(el)) {
+    el.classList.add(className)
+  }
+}
+
+export const removeClass = (el, className) => {
+  if (className && isElement(el)) {
+    el.classList.remove(className)
+  }
+}

src/utils/object.js

@@ -0,0 +1,2 @@
+export const assign = Object.assign
+export const keys = Object.keys

src/utils/pluck-props.js

@@ -0,0 +1,20 @@
+import { keys } from './object'
+import { isArray } from './array'
+
+function identity (x) {
+  return x
+}
+/**
+ * Given an array of properties or an object of property keys,
+ * plucks all the values off the target object.
+ * @param {{}|string[]} keysToPluck
+ * @param {{}} objToPluck
+ * @param {Function} transformFn
+ * @return {{}}
+ */
+export default function pluckProps (keysToPluck, objToPluck, transformFn = identity) {
+  return (isArray(keysToPluck) ? keysToPluck.slice() : keys(keysToPluck)).reduce((memo, prop) => {
+    // eslint-disable-next-line no-sequences
+    return (memo[transformFn(prop)] = objToPluck[prop]), memo
+  }, {})
+}