public/javascript/libs/select2.js
function (val, triggerChange) {
            var oldData, self=this, changeDetails;

            if (arguments.length === 0) {
                return this.getVal();
            }

            oldData=this.data();
            if (!oldData.length) oldData=[];

            // val is an id. !val is true for [undefined,null,'',0] - 0 is legal
            if (!val && val !== 0) {
                this.opts.element.val("");
                this.updateSelection([]);
                this.clearSearch();
                if (triggerChange) {
                    this.triggerChange({added: this.data(), removed: oldData});
                }
                return;
            }

            // val is a list of ids
            this.setVal(val);

            if (this.select) {
                this.opts.initSelection(this.select, this.bind(this.updateSelection));
                if (triggerChange) {
                    this.triggerChange(this.buildChangeDetails(oldData, this.data()));
                }
            } else {
                if (this.opts.initSelection === undefined) {
                    throw new Error("val() cannot be called if initSelection() is not defined");
                }

                this.opts.initSelection(this.opts.element, function(data){
                    var ids=$.map(data, self.id);
                    self.setVal(ids);
                    self.updateSelection(data);
                    self.clearSearch();
                    if (triggerChange) {
                        self.triggerChange(this.buildChangeDetails(oldData, this.data()));
                    }
                });
            }
            this.clearSearch();
        }
function (val, triggerChange) {
            var oldData, self=this, changeDetails;

            if (arguments.length === 0) {
                return this.getVal();
            }

            oldData=this.data();
            if (!oldData.length) oldData=[];

            // val is an id. !val is true for [undefined,null,'',0] - 0 is legal
            if (!val && val !== 0) {
                this.opts.element.val("");
                this.updateSelection([]);
                this.clearSearch();
                if (triggerChange) {
                    this.triggerChange({added: this.data(), removed: oldData});
                }
                return;
            }

            // val is a list of ids
            this.setVal(val);

            if (this.select) {
                this.opts.initSelection(this.select, this.bind(this.updateSelection));
                if (triggerChange) {
                    this.triggerChange(this.buildChangeDetails(oldData, this.data()));
                }
            } else {
                if (this.opts.initSelection === undefined) {
                    throw new Error("val() cannot be called if initSelection() is not defined");
                }

                this.opts.initSelection(this.opts.element, function(data){
                    var ids=$.map(data, self.id);
                    self.setVal(ids);
                    self.updateSelection(data);
                    self.clearSearch();
                    if (triggerChange) {
                        self.triggerChange(this.buildChangeDetails(oldData, this.data()));
                    }
                });
            }
            this.clearSearch();
        }
multi