$(document).ready(function () {
    let example;

    $.getJSON( "setting.json", function(data) {

        // create object based on settings
        example = new ExampleObject(data);

    }).fail(function(e) {
        console.warn(e);
    }).always(function() {
        console.log("ExampleObject after json call: ");
        console.log(example);

        window.exampleObject = example; // is still undefined in other js file cause that runs before this finishes.
    });

    window.exampleObject = example;     // is undefined cause json fetch finishes after setting this.
});

class ExampleObject{
    constructor(settings){
        this.width = settings.width;
        this.height = settings.height;
    }
    setWidth(width){
        this.width = width;
    }
    setHeight(height){
        this.height = height;
    }
}

{
    "width": 3,
    "height": 4
}

$(document).ready(function () {

    // get object from global object
    console.log(window.exampleObject);

    // cant run this line since window.exampleObject is undefined.
    window.exampleObject.setWidth(6);
    console.log(window.exampleObject);
});