check if checkbox is checked javascript

//using plane javascript 
if(document.getElementById('on_or_off_checkbox').checked) {
    //I am checked
} 

//using jQuery
if($('#on_or_off_checkbox').is(':checked')){
    //I am checked
}if(document.getElementById('on_or_off_checkbox').checked) {
    //I am checked
}else{
	//I am not checked
}document.getElementById("checkbox").checked;<input type="checkbox" onchange="doSomething(this)">

function doSomething(element){
   var isChecked=element.checked;
	//do some action if it is checked
}        
            
        
     const cb = document.getElementById('accept');
console.log(cb.checked);<script type=text/javascript>
  function validate(){
    if (remember.checked == 1){
      alert("checked") ;
    } else {
      alert("You didn't check it! Let me check it for you.")
    }
  }
</script>

<input id="remember" name="remember" type="checkbox" onclick="validate()" />