loadJSON(    url: string,    ok: { (arg0: any): void; (_value: any): any },    err: {        (arg0: string | ProgressEvent<XMLHttpRequestEventTarget>): void;        (_value: any): any;    },): void Parameters
- url: string
 - ok: { (arg0: any): void; (_value: any): any }
 - err: {
    (arg0: string | ProgressEvent<XMLHttpRequestEventTarget>): void;
    (_value: any): any;
} 
Returns void