我可以一次跟踪输入字段的文本更改，而不是每个输入？

Question

I have a basic text input field and, for data analytics purposes, I want to track every time a user edits the text in that field as they edit it. I have this code so far:

 var input = document.querySelector("#inputId");
 input.oninput = function (e) {
                   alert("changed"); 
                 }

The issue is that this fires every time the user deletes or adds a character, whereas I only want to know one single time that they are changing the text in the text field. Is there a way to achieve this? I am new to jQuery and JavaScript so any direction would be really appreciated, thank you!

Answer 1

You can try using Parameters option once: true :

once : A Boolean indicating that the listener should be invoked at most once after being added. If true , the listener would be automatically removed when invoked.

Please Note: Internet Explorer yet to support this parameter characteristic.

 var input = document.querySelector("#inputId"); input.addEventListener('input', () => { alert("changed"); }, { once: true });

 <input id="inputId"/>

Answer 2

If you only want the event handler to fire once per element, then you need to remove the event handler the first time it runs:

var input = document.querySelector("#inputId");
input.addEventListener('input', yourFunc);

function yourFunc(e) {
  alert("changed");
  this.removeEventListener('input', yourFunc);
}

Note the use of addEventListener() and removeEventListener() instead of the outdated oninput property.

As you've tagged jQuery in the question you can also achieve it in this manner, using one() :

$('#inputId').one('input', function() {
  alert('changed');
});

Answer 3

It sounds like you want to bind to the onchange event instead: it is fired when the input value is "finalized" by the user, eg when he/she blurs from the field:

 var input = document.querySelector("#inputId"); input.addEventListener('change', (e) => console.log('changed', e.target.value));

 <input type="text" id="inputId" />

Answer 4

Just remove function when it call

 let input = document.querySelector("#inputId"); input.oninput = function (e) { alert("changed"); input.oninput = undefined; }

 <input id="inputId">