Add Global Variables to Vue JS Templates

Oct 3, 2022

You can't access variables on the window object from Vue 3 templates. However, you can set the config.globalProperties property on your Vue app to register global variables and methods that any template can access.

const app = Vue.createApp();

// Now any template can access `answer` and `capitalizeFirstLetter()`
app.config.globalProperties = {
  answer: 42,
  capitalizeFirstLetter(str) {
    if (!str) {
      return '';
    return str.slice(0, 1).toUpperCase() + str.slice(1);

With this code, you can do {{answer}} anywhere in a component's template property and 42 will render. You can also use {{capitalizeFirstLetter(name)}} to capitalize the first letter of the name property in any template.

If a component has a naming conflict with config.globalProperties, the component has the priority. For example, if you have a component with an answer data property, like data: () => ({ answer: 99 }), {{answer}} will render 99, not the global value 42.

When to Use Global Properties

We make heavy use of global properties for well-defined formatting logic, like the previous capitalizeFirstLetter() example. There are many similar cases when you want to format a string or a date in the same way across multiple components, and defining a global property saves you from having to manually define the same method on multiple components.

We only recommend using global properties for methods, not objects or values. Global properties aren't tied into Vue reactivity, so updating answer won't update answer automatically everywhere Vue renders answer. We don't recommend accessing config values, like API keys, in Vue templates, so there is no need to put API keys in config.globalProperties.

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