Return false from the anonymous function:
$(xml).find("strengths").each(function() {
// Code
// To escape from this block based on a condition:
if (something) return false;
});
From the documentation of the each method:
Returning 'false' from within the each function completely stops the loop through all of the elements (this is like using a 'break' with a normal loop). Returning 'true' from within the loop skips to the next iteration (this is like using a 'continue' with a normal loop).