How to show an alert when less than 5 words is entered in textbox

Question

当用户在 vanilla Javascript 中的文本框中输入小于限制时，如何显示警报。

Answer 1

 let input = document.getElementById('input') // alerts at 6 characters if (input.value.length > 5) { alert('Your alert'); }

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

Answer 2

我通过

<input type="text" onblur="if (this.value.length < 5){alert('Your alert'); }" >