javascript - When should I used Douglas Crockfords implementation of "that"? -

in douglas crockford's article, private members in javascript, uses variable "that" refer "this" use in privileged method of class. have been using "this.publicmember" in code , seems work right. think time need use "that" if calling function "this" different, i.e. calling settimeout. when should use / not use "that" ?

function container(param) {     function dec() {         if (secret > 0) {             secret -= 1;             return true;         } else {             return false;         }     }      this.member = param;     var secret = 3;     var = this;      this.service = function () {         return dec() ? that.member : null;     }; } 

versus:

    this.service = function () {         return dec() ? this.member : null;     }; 

he writes in article:

by convention, make private that variable. used make object available private methods.

then uses that everywhere, avoid issues unbound functions (like settimeout mentioned) , able switch "method" between private , privileged. since method instance-specific anyway (not inherited prototype or so), doesn't hurt make bound , access 1 more closure variable.