dat.gui/src/controllers/boolean.js

DAT.GUI.BooleanController = function() {

    this.type = "boolean";
    DAT.GUI.Controller.apply(this, arguments);

    var _this = this;
    var input = document.createElement('input');
    input.setAttribute('type', 'checkbox');

    if(arguments[3]) {
      input.checked = true;
      this.setValue(true);
    } else {
      input.checked = false;
      this.setValue(false);
    }

    this.domElement.addEventListener('click', function(e) {
        input.checked = !input.checked;
        e.preventDefault();
        _this.setValue(input.checked);
    }, false);

    input.addEventListener('mouseup', function(e) {
        input.checked = !input.checked; // counteracts default.
    }, false);

    this.domElement.style.cursor = "pointer";
    this.propertyNameElement.style.cursor = "pointer";
    this.domElement.appendChild(input);

    this.updateDisplay = function() {
        input.checked = _this.getValue();
    };


    this.setValue = function(val) {
        if (typeof val != "boolean") {
            try {
                val = eval(val);
            } catch (e) {}
        }
        return DAT.GUI.Controller.prototype.setValue.call(this, val);
    };

};
DAT.GUI.extendController(DAT.GUI.BooleanController);