[Vuejs]-Text input placeholder returning something it is not supposed to

String is an object constructor in JavaScript.

• The Vue data object needs to return an object.

• Each key should initialize a value or undefined/null

• Reactive Vue data types are infered. See this on types in Vue.

Initialize the value as a empty string, like this:

{
    query: ""
}

or undefined like this

{
    query: undefined
}