Trying to figure out which approach is better or cleaner or recommended.

apply-vs-scope-saving.js

/**
 * Assume jQuery.
 *
 * Which approach is better?
 */

this.someClass = 'some-class';

// Save the scope for later use
var that = this;

this.$el.find('.some-selector').slideDown(400, function () {
  that.$el.addClass(that.someClass);
});


// Use apply for the scope

this.$el.find('.some-selector').slideDown(400, function () {
  this.$el.addClass(this.someClass);
}.apply(this));