bootstrap-vue · tmorehouse · Aug 26, 2019 · Aug 23, 2019 · Aug 23, 2019 · Aug 23, 2019
diff --git a/src/components/form-textarea/README.md b/src/components/form-textarea/README.md
@@ -172,11 +172,10 @@ disabled in auto-height mode.
 
 Auto-height works by computing the resulting height via CSS queries, hence the input has to be in
 document (DOM) and visible (not hidden via `display: none`). Initial height is computed on mount. If
-the `b-form-text-area` is visually hidden on mount, the auto height cannot be computed.
-
-In situations where the text area may initially be hidden visually (i.e. in non-lazy `b-tab`
-components or non-lazy static `b-modal`), you may want to use `v-if` to delay mouting (lazy mount),
-or delay setting the value of `b-form-textarea` until it's visually hidden parent is shown.
+the browser client supports [`IntersectionObserver`](https://caniuse.com/#feat=intersectionobserver)
+(either natively or via [a polyfill](/docs#js)), `<b-form-textarea>` will take advantage of this to
+determine when the textarea becomes visible and will then compute the height. Refer to the
+[Browser support](/docs#browser) section on the getting started page.
 
 ## Contextual states
 

diff --git a/src/components/form-textarea/form-textarea.js b/src/components/form-textarea/form-textarea.js
@@ -1,19 +1,25 @@
 import Vue from '../../utils/vue'
+import { VBVisible } from '../../directives/visible'
 import idMixin from '../../mixins/id'
 import formMixin from '../../mixins/form'
 import formSizeMixin from '../../mixins/form-size'
 import formStateMixin from '../../mixins/form-state'
 import formTextMixin from '../../mixins/form-text'
 import formSelectionMixin from '../../mixins/form-selection'
 import formValidityMixin from '../../mixins/form-validity'
-import { getCS, isVisible } from '../../utils/dom'
+import listenOnRootMixin from '../../mixins/listen-on-root'
+import { getCS, isVisible, requestAF } from '../../utils/dom'
 import { isNull } from '../../utils/inspect'
 
 // @vue/component
 export const BFormTextarea = /*#__PURE__*/ Vue.extend({
   name: 'BFormTextarea',
+  directives: {
+    'b-visible': VBVisible
+  },
   mixins: [
     idMixin,
+    listenOnRootMixin,
     formMixin,
     formSizeMixin,
     formStateMixin,
@@ -48,7 +54,6 @@ export const BFormTextarea = /*#__PURE__*/ Vue.extend({
   },
   data() {
     return {
-      dontResize: true,
       heightInPx: null
     }
   },
@@ -60,64 +65,52 @@ export const BFormTextarea = /*#__PURE__*/ Vue.extend({
         resize: !this.computedRows || this.noResize ? 'none' : null
       }
       if (!this.computedRows) {
-        // Conditionaly set the computed CSS height when auto rows/height is enabled.
-        // We avoid setting the style to null, which can override user manual resize handle.
+        // Conditionally set the computed CSS height when auto rows/height is enabled
+        // We avoid setting the style to `null`, which can override user manual resize handle
         styles.height = this.heightInPx
         // We always add a vertical scrollbar to the textarea when auto-height is
-        // enabled so that the computed height calcaultion returns a stable value.
+        // enabled so that the computed height calculation returns a stable value
         styles.overflowY = 'scroll'
       }
       return styles
     },
     computedMinRows() {
-      // Ensure rows is at least 2 and positive (2 is the native textarea value).
-      // A value of 1 can cause issues in some browsers, and most browsers only support
-      // 2 as the smallest value.
+      // Ensure rows is at least 2 and positive (2 is the native textarea value)
+      // A value of 1 can cause issues in some browsers, and most browsers
+      // only support 2 as the smallest value
       return Math.max(parseInt(this.rows, 10) || 2, 2)
     },
     computedMaxRows() {
       return Math.max(this.computedMinRows, parseInt(this.maxRows, 10) || 0)
     },
     computedRows() {
-      // This is used to set the attribute 'rows' on the textarea.
-      // If auto-height is enabled, then we return null as we use CSS to control height.
+      // This is used to set the attribute 'rows' on the textarea
+      // If auto-height is enabled, then we return `null` as we use CSS to control height
       return this.computedMinRows === this.computedMaxRows ? this.computedMinRows : null
     }
   },
   watch: {
-    dontResize(newVal, oldval) {
-      if (!newVal) {
-        this.setHeight()
-      }
-    },
     localValue(newVal, oldVal) {
       this.setHeight()
     }
   },
   mounted() {
-    // Enable opt-in resizing once mounted
-    this.$nextTick(() => {
-      this.dontResize = false
-    })
-  },
-  activated() {
-    // If we are being re-activated in <keep-alive>, enable opt-in resizing
-    this.$nextTick(() => {
-      this.dontResize = false
-    })
-  },
-  deactivated() {
-    // If we are in a deactivated <keep-alive>, disable opt-in resizing
-    this.dontResize = true
-  },
-  beforeDestroy() {
-    /* istanbul ignore next */
-    this.dontResize = true
+    this.setHeight()
   },
   methods: {
+    // Called by intersection observer directive
+    visibleCallback(visible) /* istanbul ignore next */ {
+      if (visible) {
+        // We use a `$nextTick()` here just to make sure any
+        // transitions or portalling have completed
+        this.$nextTick(this.setHeight)
+      }
+    },
     setHeight() {
       this.$nextTick(() => {
-        this.heightInPx = this.computeHeight()
+        requestAF(() => {
+          this.heightInPx = this.computeHeight()
+        })
       })
     },
     computeHeight() /* istanbul ignore next: can't test getComputedStyle in JSDOM */ {
@@ -127,7 +120,7 @@ export const BFormTextarea = /*#__PURE__*/ Vue.extend({
 
       const el = this.$el
 
-      // Element must be visible (not hidden) and in document.
+      // Element must be visible (not hidden) and in document
       // Must be checked after above checks
       if (!isVisible(el)) {
         return null
@@ -153,18 +146,18 @@ export const BFormTextarea = /*#__PURE__*/ Vue.extend({
       // Probe scrollHeight by temporarily changing the height to `auto`
       el.style.height = 'auto'
       const scrollHeight = el.scrollHeight
-      // Place the original old height back on the element, just in case this computedProp
-      // returns the same value as before.
+      // Place the original old height back on the element, just in case `computedProp`
+      // returns the same value as before
       el.style.height = oldHeight
 
-      // Calculate content height in "rows" (scrollHeight includes padding but not border)
+      // Calculate content height in 'rows' (scrollHeight includes padding but not border)
       const contentRows = Math.max((scrollHeight - padding) / lineHeight, 2)
       // Calculate number of rows to display (limited within min/max rows)
       const rows = Math.min(Math.max(contentRows, this.computedMinRows), this.computedMaxRows)
       // Calculate the required height of the textarea including border and padding (in pixels)
       const height = Math.max(Math.ceil(rows * lineHeight + offset), minHeight)
 
-      // Computed height remains the larger of oldHeight and new height,
+      // Computed height remains the larger of `oldHeight` and new `height`,
       // when height is in `sticky` mode (prop `no-auto-shrink` is true)
       if (this.noAutoShrink && (parseFloat(oldHeight) || 0) > height) {
         return oldHeight
@@ -184,9 +177,13 @@ export const BFormTextarea = /*#__PURE__*/ Vue.extend({
       directives: [
         {
           name: 'model',
-          rawName: 'v-model',
-          value: self.localValue,
-          expression: 'localValue'
+          value: self.localValue
+        },
+        {
+          name: 'b-visible',
+          value: this.visibleCallback,
+          // If textarea is within 640px of viewport, consider it visible
+          modifiers: { '640': true }
         }
       ],
       attrs: {

diff --git a/src/components/form-textarea/form-textarea.spec.js b/src/components/form-textarea/form-textarea.spec.js
@@ -774,52 +774,6 @@ describe('form-textarea', () => {
     input.destroy()
   })
 
-  it('activate and deactivate hooks work (keepalive)', async () => {
-    const Keepalive = {
-      template:
-        '<div><keep-alive>' +
-        '<b-form-textarea ref="textarea" v-if="show" v-model="value"></b-form-textarea>' +
-        '<p v-else></p>' +
-        '</keep-alive></div>',
-      components: { BFormTextarea },
-      props: { show: true },
-      data() {
-        return { value: '' }
-      }
-    }
-
-    const keepalive = mount(Keepalive, {
-      attachToDocument: true,
-      propsData: {
-        show: true
-      }
-    })
-
-    expect(keepalive).toBeDefined()
-
-    const textarea = keepalive.find(BFormTextarea)
-    expect(textarea).toBeDefined()
-    expect(textarea.isVueInstance()).toBe(true)
-
-    // Check that the internal dontResize flag is now false
-    await keepalive.vm.$nextTick()
-    expect(textarea.vm.dontResize).toEqual(false)
-
-    // v-if the component out of document
-    keepalive.setProps({ show: false })
-    // Check that the internal dontResize flag is now true
-    await keepalive.vm.$nextTick()
-    expect(textarea.vm.dontResize).toEqual(true)
-
-    // v-if the component out of document
-    keepalive.setProps({ show: true })
-    // Check that the internal dontResize flag is now false
-    await keepalive.vm.$nextTick()
-    expect(textarea.vm.dontResize).toEqual(false)
-
-    keepalive.destroy()
-  })
-
   it('trim modifier prop works', async () => {
     const input = mount(BFormTextarea, {
       attachToDocument: true,

diff --git a/src/components/tabs/README.md b/src/components/tabs/README.md
@@ -22,7 +22,7 @@ For navigation based tabs (i.e. tabs that would change the URL), use the
 
 **Tip:** You should supply each child `<b-tab>` component a unique `key` value if dynamically adding
 or removing `<b-tab>` components (i.e. `v-if` or for loops). The `key` attribute is a special Vue
-attribute, see https://vuejs.org/v2/api/#key).
+attribute, see https://vuejs.org/v2/api/#key.
 
 ## Cards integration
 
@@ -479,7 +479,7 @@ order to use these methods.
           </b-button>
         </b-tab>
 
-        <!-- New Tab Button (Using tabs slot) -->
+        <!-- New Tab Button (Using tabs-end slot) -->
         <template slot="tabs-end">
           <b-nav-item @click.prevent="newTab" href="#"><b>+</b></b-nav-item>
         </template>