Question

var outer = new Array();
var inner = new Array();

inner[0] = "target";
outer[0] = inner;

So in Javascript whats the correct syntax to access the string target?

var target = outer[0][0];   //correct

or sth. like

var target = outer[0].[0];  //false don´t use

Answer 1

To access an array you need to use

var target = outer[0][0];

The dot notation you seem to be confusing in your second suggestion is used to access object properties. So if you would have

var outer = new Object();
var inner = new Object();

inner.item = "target";
outer.item = inner;

you would use outer.item.item to access "target".