Align behavior with Primer guidance behind only-validate-on-blur toggle

README.md

@@ -158,6 +158,8 @@ npm install
 npm test
 ```
 
+For local development, uncomment the line at the bottom of `examples/index` and serve the page using `npx serve`.
+
 ## License
 
 Distributed under the MIT license. See LICENSE for details.

custom-elements.json

@@ -198,6 +198,21 @@
                 "text": "string"
               },
               "readonly": true
+            },
+            {
+              "kind": "field",
+              "name": "validateOnKeystroke",
+              "type": {
+                "text": "boolean"
+              }
+            },
+            {
+              "kind": "field",
+              "name": "onlyValidateOnBlur",
+              "type": {
+                "text": "boolean"
+              },
+              "readonly": true
             }
           ],
           "attributes": [

examples/index.html

@@ -12,7 +12,6 @@
     <main>
       <h1>auto-check-element</h1>
       <h2>Simple form</h2>
-      <p>Input 422 for an error response.</p>
       <h2 tabindex="-1" id="success1" class="success" hidden>Your submission was successful</h2>
       <form>
         <p>All fields marked with * are required</p>
@@ -38,6 +37,19 @@ <h2 tabindex="-1" id="success2" class="success" hidden>Your submission was succe
         </auto-check>
         <button value="2" name="form">submit</button>
       </form>
+
+      <h2>only-validate-on-blur</h2>
+      <h2 tabindex="-1" id="success3" class="success" hidden>Your submission was successful</h2>
+      <form>
+        <p>All fields marked with * are required</p>
+
+        <label for="simple-field2">Desired username*:</label>
+        <auto-check csrf="foo" src="/demo" required only-validate-on-blur>
+          <input id="simple-field2" autofocus name="foo" required aria-describedby="state3" />
+          <p id="state3" aria-atomic="true" aria-live="polite" class="state"></p>
+        </auto-check>
+        <button value="3" name="form">submit</button>
+      </form>
     </main>
 
     <script>
@@ -97,6 +109,6 @@ <h2 tabindex="-1" id="success2" class="success" hidden>Your submission was succe
     </script>
 
     <script type="module" src="https://unpkg.com/@github/auto-check-element@latest"></script>
-    <!-- <script type="module" src="../dist/index.js" defer></script> -->
+    <!-- <script type="module" src="../dist/bundle.js" defer></script> -->
   </body>
 </html>

src/auto-check-element.ts

@@ -105,8 +105,10 @@ export class AutoCheckElement extends HTMLElement {
     const state = {check: checker, controller: null}
     states.set(this, state)
 
-    input.addEventListener('input', setLoadingState)
-    input.addEventListener('input', checker)
+    const changeHandler = handleChange.bind(null, checker)
+
+    input.addEventListener('blur', changeHandler)
+    input.addEventListener('input', changeHandler)
     input.autocomplete = 'off'
     input.spellcheck = false
   }
@@ -185,6 +187,43 @@ export class AutoCheckElement extends HTMLElement {
   get httpMethod(): string {
     return AllowedHttpMethods[this.getAttribute('http-method') as keyof typeof AllowedHttpMethods] || 'POST'
   }
+
+  set validateOnKeystroke(enabled: boolean) {
+    if (enabled) {
+      this.setAttribute('validate-on-keystroke', '')
+    } else {
+      this.removeAttribute('validate-on-keystroke')
+    }
+  }
+
+  get validateOnKeystroke(): boolean {
+    const value = this.getAttribute('validate-on-keystroke')
+    return value === 'true' || value === ''
+  }
+
+  get onlyValidateOnBlur(): boolean {
+    const value = this.getAttribute('only-validate-on-blur')
+    return value === 'true' || value === ''
+  }
+}
+
+function handleChange(checker: () => void, event: Event) {
+  const input = event.currentTarget
+  if (!(input instanceof HTMLInputElement)) return
+
+  const autoCheckElement = input.closest('auto-check')
+  if (!(autoCheckElement instanceof AutoCheckElement)) return
+
+  if (input.value.length === 0) return
+
+  if (
+    (event.type !== 'blur' && !autoCheckElement.onlyValidateOnBlur) || // Existing default behavior
+    (event.type === 'blur' && autoCheckElement.onlyValidateOnBlur) || // Only validate on blur if only-validate-on-blur is set
+    (autoCheckElement.onlyValidateOnBlur && autoCheckElement.validateOnKeystroke) // Only validate on key inputs in only-validate-on-blur mode if validate-on-keystroke is set (when input is invalid)
+  ) {
+    checker()
+    setLoadingState(event)
+  }
 }
 
 function setLoadingState(event: Event) {
@@ -298,8 +337,18 @@ async function check(autoCheckElement: AutoCheckElement) {
       if (autoCheckElement.required) {
         input.setCustomValidity('')
       }
+      // We do not have good test coverage for this code path.
+      // To test, ensure that the input only validates on blur
+      // once it has been "healed" by a valid input after
+      // previously being in an invalid state.
+      if (autoCheckElement.onlyValidateOnBlur) {
+        autoCheckElement.validateOnKeystroke = false
+      }
       input.dispatchEvent(new AutoCheckSuccessEvent(response.clone()))
     } else {
+      if (autoCheckElement.onlyValidateOnBlur) {
+        autoCheckElement.validateOnKeystroke = true
+      }
       const event = new AutoCheckErrorEvent(response.clone())
       input.dispatchEvent(event)
       if (autoCheckElement.required) {

test/auto-check.js

@@ -22,6 +22,65 @@ describe('auto-check element', function () {
     })
   })
 
+  describe('when only-validate-on-blur is true', function () {
+    let checker
+    let input
+
+    beforeEach(function () {
+      const container = document.createElement('div')
+      container.innerHTML = `
+        <auto-check csrf="foo" src="/success" only-validate-on-blur>
+          <input>
+        </auto-check>`
+      document.body.append(container)
+
+      checker = document.querySelector('auto-check')
+      input = checker.querySelector('input')
+    })
+
+    it('does not emit on initial input change', async function () {
+      const events = []
+      input.addEventListener('auto-check-start', event => events.push(event.type))
+      triggerInput(input, 'hub')
+      assert.deepEqual(events, [])
+    })
+
+    it('does not emit on blur if input is blank', async function () {
+      const events = []
+      input.addEventListener('auto-check-start', event => events.push(event.type))
+      triggerBlur(input)
+      assert.deepEqual(events, [])
+    })
+
+    it('emits on blur', async function () {
+      const events = []
+      input.addEventListener('auto-check-start', event => events.push(event.type))
+      triggerInput(input, 'hub')
+      triggerBlur(input)
+      assert.deepEqual(events, ['auto-check-start'])
+    })
+
+    it('emits on input change if input is invalid after blur', async function () {
+      const events = []
+      input.addEventListener('auto-check-start', event => events.push(event.type))
+
+      checker.src = '/fail'
+      triggerInput(input, 'hub')
+      triggerBlur(input)
+      await once(input, 'auto-check-complete')
+      triggerInput(input, 'hub2')
+      triggerInput(input, 'hub3')
+
+      assert.deepEqual(events, ['auto-check-start', 'auto-check-start', 'auto-check-start'])
+    })
+
+    afterEach(function () {
+      document.body.innerHTML = ''
+      checker = null
+      input = null
+    })
+  })
+
   describe('required attribute', function () {
     let checker
     let input
@@ -331,3 +390,7 @@ function triggerInput(input, value) {
   input.value = value
   return input.dispatchEvent(new InputEvent('input'))
 }
+
+function triggerBlur(input) {
+  return input.dispatchEvent(new FocusEvent('blur'))
+}