Slightly refactor pipeline schedules form in preparation for additions

app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.js

-import Vue from 'vue';
-import Translate from '../../vue_shared/translate';
-
-Vue.use(Translate);
-
-const inputNameAttribute = 'schedule[cron]';
-
-export default {
-  props: {
-    initialCronInterval: {
-      type: String,
-      required: false,
-      default: '',
-    },
-  },
-  data() {
-    return {
-      inputNameAttribute,
-      cronInterval: this.initialCronInterval,
-      cronIntervalPresets: {
-        everyDay: '0 4 * * *',
-        everyWeek: '0 4 * * 0',
-        everyMonth: '0 4 1 * *',
-      },
-      cronSyntaxUrl: 'https://en.wikipedia.org/wiki/Cron',
-      customInputEnabled: false,
-    };
-  },
-  computed: {
-    intervalIsPreset() {
-      return _.contains(this.cronIntervalPresets, this.cronInterval);
-    },
-    // The text input is editable when there's a custom interval, or when it's
-    // a preset interval and the user clicks the 'custom' radio button
-    isEditable() {
-      return !!(this.customInputEnabled || !this.intervalIsPreset);
-    },
-  },
-  methods: {
-    toggleCustomInput(shouldEnable) {
-      this.customInputEnabled = shouldEnable;
-
-      if (shouldEnable) {
-        // We need to change the value so other radios don't remain selected
-        // because the model (cronInterval) hasn't changed. The server trims it.
-        this.cronInterval = `${this.cronInterval} `;
-      }
-    },
-  },
-  created() {
-    if (this.intervalIsPreset) {
-      this.enableCustomInput = false;
-    }
-  },
-  watch: {
-    cronInterval() {
-      // updates field validation state when model changes, as
-      // glFieldError only updates on input.
-      Vue.nextTick(() => {
-        gl.pipelineScheduleFieldErrors.updateFormValidityState();
-      });
-    },
-  },
-  template: `
-    <div class="interval-pattern-form-group">
-      <div class="cron-preset-radio-input">
-        <input
-          id="custom"
-          class="label-light"
-          type="radio"
-          :name="inputNameAttribute"
-          :value="cronInterval"
-          :checked="isEditable"
-          @click="toggleCustomInput(true)"
-        />
-
-        <label for="custom">
-          {{ s__('PipelineSheduleIntervalPattern|Custom') }}
-        </label>
-
-        <span class="cron-syntax-link-wrap">
-          (<a :href="cronSyntaxUrl" target="_blank">{{ __('Cron syntax') }}</a>)
-        </span>
-      </div>
-
-      <div class="cron-preset-radio-input">
-        <input
-          id="every-day"
-          class="label-light"
-          type="radio"
-          v-model="cronInterval"
-          :name="inputNameAttribute"
-          :value="cronIntervalPresets.everyDay"
-          @click="toggleCustomInput(false)"
-        />
-
-        <label class="label-light" for="every-day">
-          {{ __('Every day (at 4:00am)') }}
-        </label>
-      </div>
-
-      <div class="cron-preset-radio-input">
-        <input
-          id="every-week"
-          class="label-light"
-          type="radio"
-          v-model="cronInterval"
-          :name="inputNameAttribute"
-          :value="cronIntervalPresets.everyWeek"
-          @click="toggleCustomInput(false)"
-        />
-
-        <label class="label-light" for="every-week">
-          {{ __('Every week (Sundays at 4:00am)') }}
-        </label>
-      </div>
-
-      <div class="cron-preset-radio-input">
-        <input
-          id="every-month"
-          class="label-light"
-          type="radio"
-          v-model="cronInterval"
-          :name="inputNameAttribute"
-          :value="cronIntervalPresets.everyMonth"
-          @click="toggleCustomInput(false)"
-        />
-
-        <label class="label-light" for="every-month">
-          {{ __('Every month (on the 1st at 4:00am)') }}
-        </label>
-      </div>
-
-      <div class="cron-interval-input-wrapper">
-        <input
-          id="schedule_cron"
-          class="form-control inline cron-interval-input"
-          type="text"
-          :placeholder="__('Define a custom pattern with cron syntax')"
-          required="true"
-          v-model="cronInterval"
-          :name="inputNameAttribute"
-          :disabled="!isEditable"
-        />
-      </div>
-    </div>
-  `,
-};

app/assets/javascripts/pipeline_schedules/components/interval_pattern_input.vue

+<script>
+  export default {
+    props: {
+      initialCronInterval: {
+        type: String,
+        required: false,
+        default: '',
+      },
+    },
+    data() {
+      return {
+        inputNameAttribute: 'schedule[cron]',
+        cronInterval: this.initialCronInterval,
+        cronIntervalPresets: {
+          everyDay: '0 4 * * *',
+          everyWeek: '0 4 * * 0',
+          everyMonth: '0 4 1 * *',
+        },
+        cronSyntaxUrl: 'https://en.wikipedia.org/wiki/Cron',
+        customInputEnabled: false,
+      };
+    },
+    computed: {
+      intervalIsPreset() {
+        return _.contains(this.cronIntervalPresets, this.cronInterval);
+      },
+      // The text input is editable when there's a custom interval, or when it's
+      // a preset interval and the user clicks the 'custom' radio button
+      isEditable() {
+        return !!(this.customInputEnabled || !this.intervalIsPreset);
+      },
+    },
+    methods: {
+      toggleCustomInput(shouldEnable) {
+        this.customInputEnabled = shouldEnable;
+
+        if (shouldEnable) {
+          // We need to change the value so other radios don't remain selected
+          // because the model (cronInterval) hasn't changed. The server trims it.
+          this.cronInterval = `${this.cronInterval} `;
+        }
+      },
+    },
+    created() {
+      if (this.intervalIsPreset) {
+        this.enableCustomInput = false;
+      }
+    },
+    watch: {
+      cronInterval() {
+        // updates field validation state when model changes, as
+        // glFieldError only updates on input.
+        this.$nextTick(() => {
+          gl.pipelineScheduleFieldErrors.updateFormValidityState();
+        });
+      },
+    },
+  };
+</script>
+
+<template>
+  <div class="interval-pattern-form-group">
+    <div class="cron-preset-radio-input">
+      <input
+        id="custom"
+        class="label-light"
+        type="radio"
+        :name="inputNameAttribute"
+        :value="cronInterval"
+        :checked="isEditable"
+        @click="toggleCustomInput(true)"
+      />
+
+      <label for="custom">
+        {{ s__('PipelineSheduleIntervalPattern|Custom') }}
+      </label>
+
+      <span class="cron-syntax-link-wrap">
+        (<a :href="cronSyntaxUrl" target="_blank">{{ __('Cron syntax') }}</a>)
+      </span>
+    </div>
+
+    <div class="cron-preset-radio-input">
+      <input
+        id="every-day"
+        class="label-light"
+        type="radio"
+        v-model="cronInterval"
+        :name="inputNameAttribute"
+        :value="cronIntervalPresets.everyDay"
+        @click="toggleCustomInput(false)"
+      />
+
+      <label class="label-light" for="every-day">
+        {{ __('Every day (at 4:00am)') }}
+      </label>
+    </div>
+
+    <div class="cron-preset-radio-input">
+      <input
+        id="every-week"
+        class="label-light"
+        type="radio"
+        v-model="cronInterval"
+        :name="inputNameAttribute"
+        :value="cronIntervalPresets.everyWeek"
+        @click="toggleCustomInput(false)"
+      />
+
+      <label class="label-light" for="every-week">
+        {{ __('Every week (Sundays at 4:00am)') }}
+      </label>
+    </div>
+
+    <div class="cron-preset-radio-input">
+      <input
+        id="every-month"
+        class="label-light"
+        type="radio"
+        v-model="cronInterval"
+        :name="inputNameAttribute"
+        :value="cronIntervalPresets.everyMonth"
+        @click="toggleCustomInput(false)"
+      />
+
+      <label class="label-light" for="every-month">
+        {{ __('Every month (on the 1st at 4:00am)') }}
+      </label>
+    </div>
+
+    <div class="cron-interval-input-wrapper">
+      <input
+        id="schedule_cron"
+        class="form-control inline cron-interval-input"
+        type="text"
+        :placeholder="__('Define a custom pattern with cron syntax')"
+        required="true"
+        v-model="cronInterval"
+        :name="inputNameAttribute"
+        :disabled="!isEditable"
+      />
+    </div>
+  </div>
+</template>

app/assets/javascripts/pipeline_schedules/pipeline_schedule_form_bundle.js

 import Vue from 'vue';
-import IntervalPatternInput from './components/interval_pattern_input';
+import Translate from '../vue_shared/translate';
+import intervalPatternInput from './components/interval_pattern_input.vue';
 import TimezoneDropdown from './components/timezone_dropdown';
 import TargetBranchDropdown from './components/target_branch_dropdown';
 
-document.addEventListener('DOMContentLoaded', () => {
-  const IntervalPatternInputComponent = Vue.extend(IntervalPatternInput);
+Vue.use(Translate);
+
+function initIntervalPatternInput() {
   const intervalPatternMount = document.getElementById('interval-pattern-input');
   const initialCronInterval = intervalPatternMount ? intervalPatternMount.dataset.initialInterval : '';
 
-  new IntervalPatternInputComponent({
-    propsData: {
-      initialCronInterval,
+  return new Vue({
+    el: intervalPatternMount,
+    components: {
+      intervalPatternInput,
     },
-  }).$mount(intervalPatternMount);
+    render(createElement) {
+      return createElement('interval-pattern-input', {
+        props: {
+          initialCronInterval,
+        },
+      });
+    },
+  });
+}
+
+document.addEventListener('DOMContentLoaded', () => {
+  /* Most of the form is written in haml, but for fields with more complex behaviors,
+   * you should mount individual Vue components here. If at some point components need
+   * to share state, it may make sense to refactor the whole form to Vue */
+
+  initIntervalPatternInput();
+
+  // Initialize non-Vue JS components in the form
 
   const formElement = document.getElementById('new-pipeline-schedule-form');
+
   gl.timezoneDropdown = new TimezoneDropdown();
   gl.targetBranchDropdown = new TargetBranchDropdown();
   gl.pipelineScheduleFieldErrors = new gl.GlFieldErrors(formElement);

spec/javascripts/pipeline_schedules/interval_pattern_input_spec.js

 import Vue from 'vue';
-import IntervalPatternInput from '~/pipeline_schedules/components/interval_pattern_input';
+import Translate from '~/vue_shared/translate';
+import IntervalPatternInput from '~/pipeline_schedules/components/interval_pattern_input.vue';
+
+Vue.use(Translate);
 
 const IntervalPatternInputComponent = Vue.extend(IntervalPatternInput);
 const inputNameAttribute = 'schedule[cron]';