Why Laravel Echo not listening

Put . before event name

Chang this

mounted: function(){
        
        Echo.private('chat').listen('MessageSent', (e) => {
            console.log(e)
            
        });
    },

to this

mounted: function(){
        
        Echo.private('chat').listen('.MessageSent', (e) => {
            console.log(e)
            
        });
    },