FullCalendar 4.3.1中文模式下在IE11中显示两个月字

CalendarComponent.prototype.render = function (props) {
     this.freezeHeight();
     var title = this.computeTitle(props.dateProfile, props.viewSpec.options);
     if (title.indexOf("月月") != -1) {
         title = title.replace("月月", "月");
     }
     this._renderToolbars(props.viewSpec, props.dateProfile, props.currentDate, props.dateProfileGenerator, title);
     this.renderView(props, title);
     this.updateSize();
     this.thawHeight();
};

function htmlEscape(s) {
        if (s.indexOf("月月") != -1) {
            s = s.replace("月月", "月");
        }
        return (s + '').replace(/&/g, '&')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;')
            .replace(/'/g, '&#039;')
            .replace(/"/g, '&quot;')
            .replace(/\n/g, '<br />');
    }

Toolbar.prototype.updateTitle = function (text) {
     findElements(this.el, 'h2').forEach(function (titleEl) {
         if (text.indexOf("月月") != -1) {
             text = text.replace("月月", "月");
         }
         titleEl.innerText = text;
     });
};