Each Vue instance goes through a series of initialization steps when it’s created - for example, it needs to set up data observation, compile the template, mount the instance to the DOM, and update the DOM when data changes. Along the way, it also runs functions called lifecycle hooks, giving users the opportunity to add their own code at specific stages.
For example, the created hook can be used to run code after an instance is created:
new Vue({
data: {
a: 1
},
created: function () {
// `this` points to the vm instance
console.log('a is: ' + this.a)
}
})
There are also other hooks which will be called at different stages of the instance’s lifecycle, such as mounted, updated, and destroyed. All lifecycle hooks are called with their this context pointing to the Vue instance invoking it.
