How to get old value with onchange() event in text box with JavaScript?

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To get old value with onchange() event in text box with JavaScript, we set the old value when we click on the input.

For instance, we write

<input
  type="text"
  id="test"
  value="abc"
  onchange="onChange(this)"
  onclick="setOldValue(this)"
  oldvalue=""
/>

to add an input.

We set the onchange attribute to call the onChange function with the input as the argument.

And we set the onclick attribute to call the setOldValue function with the input as the argument.

Then we write

function setOldValue(element) {
  element.setAttribute("data-old-value", this.value);
}

function onChange(element) {
  element.setAttribute("value", this.getAttribute("data-old-value"));
}

to define the 2 functions.

In setOldValue, we set the data-old-value attribute to the input value with setAttribute.

And in onChange, we set the value attribute of the input to the data-old-value attribute value.

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