How to use js libraries in typescript if there are no definitions?

Question

JavaScript

How to load a js library into a typescript project if there are no typings for it.
used

/// <amd-dependency path="./node_modules/async" />
declare var require:(moduleId:string) => any;
....
val _ : any=require('async');

but with different libs there are some problems when compiling.
Is there a more generic way to use libraries from js .