js

blur()

html

<input type="text" id="sampleText" value="Sample Text" /> <br /><br />
<button type="button" onclick="focusInput()">Click me to gain focus</button>

js

function focusInput() {
  const textField = document.getElementById("sampleText");

  textField.focus();

  // The input will lose focus after 3 seconds
  setTimeout(() => {
    textField.blur();
  }, 3000);
}