jQuery检查不是我想要的方式

Question

So, I am creating a check with javascript/jquery, when a user fills out something it should check whether the answer is right or wrong. But whenever I try to do so it will say with each letter I fill out it's wrong untill I reach the correct answer. For instance we take the word "example". You as user should write "example", but when u are writing example it checks them as wrong untill you have written the word "example". How can I prevent such thing from happening? For it to evaluate the word after 1 or 1.5 seconds? This is my code:

function prepareCheck() {
$.getJSON('json_files/jsonData_' + ID + '.json', function(json) {
   $(document).on('keyup', '.syl-input', function() {
       var rowCounter = $(this).parent().parent().parent().parent().attr('id');
       var inputCounter = $(this).attr('id');
       var jsyl = json.main_object.main_object.exercises[rowCounter].syllables[inputCounter];
       var jsylall = json.main_object.main_object.exercises[rowCounter].syllables;
       var valueInput = $(this).val();

       console.log(jsyl);

       if (valueInput == jsyl) {
        S.addRight();
       } else if ($.inArray(valueInput, jsylall) >= -1) {
        S.addWrong();
       }
  });
});
}

Answer 1

You can use code such

setInterval(check_answer(), 1000);

for starting the check

And check_answer() checks if the answer has changed since 1 second before :

• if yes, means that the user is typing, so it's useless to check the answer, we wait he's finished to type his answer
• if no (hasn't changed), means the user isn't typing anything since 1 second, then you can launch the check...

So code can be like this :

setInterval(check_answer(), 1000);

var old_answer="";
function check_answer() {
    new_answer = $("#answer").val();
    if ( new_answer==old_answer) {
        // nothing typed since 1 second, i launch the control and display error message if answer invalid...
    }
}

Another (or complementary) strategy is to say that :

• if Keydown, then the user starting typing, so we stop the setTimeout by a clearTimeout
• if KeyUp, then the user has finished typing, so we start the setTimeout...

Sample code :

var timer;
$field_to_check.on('keyup', function () {
   clearTimeout(timer);
   timer = setTimeout(check_answer, 1000);
 });

//on keydown, clear the countdown 
$field_to_check.on('keydown', function () {
  clearTimeout(timer);
});