When initializing data-dependent components such as charts, network requests often resolve after the rendering logic has already executed. Consider a scanario where a Vue component must populate an ECharts dataset from a remote endpoint before calling setOption.

Without synchronization, the initialization method finishes before the HTTP request returns:

methods: {
  renderChart() {
    this.plot = echarts.init(this.$refs.graph);

    fetchStatistics().then(res => {
      console.log('Payload:', res.items);
      this.config.series[0].data = res.items;
    }).catch(e => console.error(e));

    console.log('Current data:', this.config.series[0].data);
    this.plot.setOption(this.config);
  }
}

Because fetchStatistics returns a Promise, the statements that follow it run immediate. The chart therefore renders with an empty or stale dataset while the network call is still pending.

JavaScript provides the async and await keywords to write asynchronous code that reads sequentially. Marking a function with async means it implicitly returns a Promise and can contain await expressoins. The await operator pauses execution until the awaited Promise settles, allowing subsequent lines to run only after the value is available.

Applying this pattern ensures the chart receives its data before rendering:

methods: {
  async renderChart() {
    this.plot = echarts.init(this.$refs.graph);

    try {
      const res = await fetchStatistics();
      console.log('Payload:', res.items);
      this.config.series[0].data = res.items;
    } catch (e) {
      console.error(e);
    }

    console.log('Current data:', this.config.series[0].data);
    this.plot.setOption(this.config);
  }
}

In Vue lifecycle hooks, mounted runs synchronously. If multiple setup routines must happen in strict order, extract them into a dedicated async method rather than calling them directly inside mounted:

methods: {
  async bootstrapView() {
    await this.fetchWorkflowMetadata();

    if (this.existingWorkflow) {
      this.determineActiveStage();
      this.restoreFormState();
      this.initializeDepartments(false, this.formSnapshot.department);
    } else {
      this.currentStage = 'apply';
    }

    await this.validateAccess();
  }
},

mounted() {
  this.bootstrapView();
}

Calling this.validateAccess() directly after this.bootstrapView() inside mounted would start both tasks concurrently, because mounted is not declared async and does not wait.

One common syntax error occurs when await is placed inside a standard callback. The operator is only valid within an async function. For example, nesting await inside a .then() callback requires that callback to be async:

// Invalid: await inside non-async callback
await searchRecords(query).then(response => {
  await removeRecord(response.results[0].id); // SyntaxError
});

// Valid:
await searchRecords(query).then(async response => {
  await removeRecord(response.results[0].id);
});

A cleaner approach is to avoid mixing Promise chains with await by storing intermediate results in variables:

const searchResult = await searchRecords(query);
await removeRecord(searchResult.results[0].id);