Move get element functionality to a helper (#33327)

Looking around on js components I found out many checks, different expressed but with same purpose.
Some of them are trying to parse string to element, others, jQuery element to js simple nodeElement etc

With this Pr, I am trying to give a standard way to parse an element

So this pr:

* Creates `getElement` helper that tries to parse an argument to element or null
* Changes `isElement` to make  explicit checks and return Boolean 
* fixes tests deficiencies

js/src/base-component.js

@@ -9,6 +9,7 @@ import Data from './dom/data'
 import {
   emulateTransitionEnd,
   execute,
+  getElement,
   getTransitionDurationFromElement
 } from './util/index'
 import EventHandler from './dom/event-handler'
@@ -23,7 +24,7 @@ const VERSION = '5.0.0'
 
 class BaseComponent {
   constructor(element) {
-    element = typeof element === 'string' ? document.querySelector(element) : element
+    element = getElement(element)
 
     if (!element) {
       return

js/src/collapse.js

@@ -7,9 +7,9 @@
 
 import {
   defineJQueryPlugin,
+  getElement,
   getSelectorFromElement,
   getElementFromSelector,
-  isElement,
   reflow,
   typeCheckConfig
 } from './util/index'
@@ -272,14 +272,7 @@ class Collapse extends BaseComponent {
   _getParent() {
     let { parent } = this._config
 
-    if (isElement(parent)) {
-      // it's a jQuery object
-      if (typeof parent.jquery !== 'undefined' || typeof parent[0] !== 'undefined') {
-        parent = parent[0]
-      }
-    } else {
-      parent = SelectorEngine.findOne(parent)
-    }
+    parent = getElement(parent)
 
     const selector = `${SELECTOR_DATA_TOGGLE}[data-bs-parent="${parent}"]`
 

js/src/dropdown.js

@@ -9,6 +9,7 @@ import * as Popper from '@popperjs/core'
 
 import {
   defineJQueryPlugin,
+  getElement,
   getElementFromSelector,
   isDisabled,
   isElement,
@@ -166,12 +167,7 @@ class Dropdown extends BaseComponent {
       if (this._config.reference === 'parent') {
         referenceElement = parent
       } else if (isElement(this._config.reference)) {
-        referenceElement = this._config.reference
-
-        // Check if it's jQuery element
-        if (typeof this._config.reference.jquery !== 'undefined') {
-          referenceElement = this._config.reference[0]
-        }
+        referenceElement = getElement(this._config.reference)
       } else if (typeof this._config.reference === 'object') {
         referenceElement = this._config.reference
       }

js/src/tooltip.js

@@ -10,6 +10,7 @@ import * as Popper from '@popperjs/core'
 import {
   defineJQueryPlugin,
   findShadowRoot,
+  getElement,
   getUID,
   isElement,
   isRTL,
@@ -256,7 +257,7 @@ class Tooltip extends BaseComponent {
     const attachment = this._getAttachment(placement)
     this._addAttachmentClass(attachment)
 
-    const container = this._getContainer()
+    const { container } = this._config
     Data.set(tip, this.constructor.DATA_KEY, this)
 
     if (!this._element.ownerDocument.documentElement.contains(this.tip)) {
@@ -385,10 +386,8 @@ class Tooltip extends BaseComponent {
       return
     }
 
-    if (typeof content === 'object' && isElement(content)) {
-      if (content.jquery) {
-        content = content[0]
-      }
+    if (isElement(content)) {
+      content = getElement(content)
 
       // content is a DOM node or a jQuery
       if (this._config.html) {
@@ -518,18 +517,6 @@ class Tooltip extends BaseComponent {
     this.getTipElement().classList.add(`${CLASS_PREFIX}-${this.updateAttachment(attachment)}`)
   }
 
-  _getContainer() {
-    if (this._config.container === false) {
-      return document.body
-    }
-
-    if (isElement(this._config.container)) {
-      return this._config.container
-    }
-
-    return SelectorEngine.findOne(this._config.container)
-  }
-
   _getAttachment(placement) {
     return AttachmentMap[placement.toUpperCase()]
   }
@@ -664,16 +651,14 @@ class Tooltip extends BaseComponent {
       }
     })
 
-    if (config && typeof config.container === 'object' && config.container.jquery) {
-      config.container = config.container[0]
-    }
-
     config = {
       ...this.constructor.Default,
       ...dataAttributes,
       ...(typeof config === 'object' && config ? config : {})
     }
 
+    config.container = config.container === false ? document.body : getElement(config.container)
+
     if (typeof config.delay === 'number') {
       config.delay = {
         show: config.delay,

js/src/util/index.js

@@ -1,3 +1,5 @@
+import SelectorEngine from '../dom/selector-engine'
+
 /**
  * --------------------------------------------------------------------------
  * Bootstrap (v5.0.0): util/index.js
@@ -100,7 +102,29 @@ const triggerTransitionEnd = element => {
   element.dispatchEvent(new Event(TRANSITION_END))
 }
 
-const isElement = obj => (obj[0] || obj).nodeType
+const isElement = obj => {
+  if (!obj || typeof obj !== 'object') {
+    return false
+  }
+
+  if (typeof obj.jquery !== 'undefined') {
+    obj = obj[0]
+  }
+
+  return typeof obj.nodeType !== 'undefined'
+}
+
+const getElement = obj => {
+  if (isElement(obj)) { // it's a jQuery object or a node element
+    return obj.jquery ? obj[0] : obj
+  }
+
+  if (typeof obj === 'string' && obj.length > 0) {
+    return SelectorEngine.findOne(obj)
+  }
+
+  return null
+}
 
 const emulateTransitionEnd = (element, duration) => {
   let called = false
@@ -238,6 +262,7 @@ const execute = callback => {
 }
 
 export {
+  getElement,
   getUID,
   getSelectorFromElement,
   getElementFromSelector,