JavaScript Scope Chain - Variable

run.js

//JavaScript Scope Chain
var mytxt = 'test1';
function echo() {
     console.log("A-->" + mytxt);
     var mytxt = 'test2';
     console.log("B-->" + mytxt);
}
echo();

/*
The result is not 
A-->test1
B-->test2
it's
A-->undefined
B-->test2
*/