About Name your functions

- Name your functions. This is helpful for stack traces. //I don't understand why this can stack traces??
   
   // bad   I think this is good,because very convenience.
    var log = function(msg) {
      console.log(msg);
    };

    // good  I can't understand why is good? I think is not necessary js style.I hope you can explain this problem for me, I really confused. thank you.
    var log = function log(msg) {
      console.log(msg);
    };