如何通过按 ESC 键（Javascript）来防止中止？

Question

I would like to prompt a string. My additional need is to not escape by pressing the ENTER or ESC key. With this method ENTER works (doesn't escape):

var f1 = '';
while (f1.length < 1) {
  f1 = prompt('Please give a value of the string!');
}

How can I reach, that this script doesn't escape by pressing ESC either? Thanks, hazazs

Answer 1

You can't. prompt is a browser function and its event cannot be prevented.

Instead, try to create your own popup window for that purpose. There are various jQuery/Bootstrap modals available.

prompt

shows a message asking the user to input text. It returns the text or, if Cancel button or Esc is clicked, null

Answer 2

prompt returns null when you click ESC button. You need to check null also in while

while (f1 == null || f1.length < 1)

Or simply

while (!f1)

Use this one:

var f1 = '';
while (!f1) {
     f1 = prompt('Please give a value of the string!');
}

Note: As Cancel and ESC both returns null, you will not be able to Cancel it though.

Answer 3

Easy. First you have to give a default value of prompt and set it to prompt and check if the prompt is empty by comparing default value with new one. If user ignore the prompt the default value is the final value. And there we will get it. I am returning false to results when user ignores or press enter or esc.

 document.getElementById("test").addEventListener("click", function() { var oldVal = 'Enter Name:'; var newVal = prompt("Enter new value:", oldVal); var results = document.getElementById("results"); if (newVal === null || newVal === oldVal) { results.innerHTML = false; //And here if the prompt is empty just do what you want. } else { results.innerHTML = true; } });

 <button id="test">Test</button> <div id="results"></div>