how to detect which key is pressed in javascript code example

Example 1: how to check if enter is pressed javascript

$('#usersearch').keydown(function(e){
    if(e.keyCode === 13){
            alert("Enter was pressed ");
     }  
});

Example 2: js when key is pressed

document.addEventListener("keypress", function(event) {
	// do stuff
});

Example 3: js keyboard input

document.addEventListener('keydown', function(event) {
    if(event.keyCode == 37) {
        alert('Left was pressed');
    }
    else if(event.keyCode == 39) {
        alert('Right was pressed');
    }
});