Q: using classes in same folder in typescript I have a class test.ts
export class Test1 {

}

I have another class usetest.ts in same folder that gives me error
import Test = require("test");//error say cannot find test
 var t = new Test.Test1();

but if I specify
 import Test = require("./test");//no error
     var t = new Test.Test1();

then there is no error. What the "./" is necessary? Can we omit it in anyway?

A: 
What the "./" is necessary?

Yes

Can we omit it in anyway?

Not easily. It needs to be in ./node_modules/test.ts for require('test') to just work. 
More
Here is the complete nodejs module spec : https://nodejs.org/api/modules.html#modules_all_together ... its a bit much but if you are doing NodeJS development I highly recommend reading it 
