KeyPress n KeyUp事件

本文介绍了KeyPress n KeyUp事件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个文本字段，应该接受 只有数字 但我的条件很少， 1当我按第一个数字'M'时应该附加 2.当我按下更多数字时，'M'应该保持在最后。 例如。 1M 12M 123M 1236M 3.当我按下退格键时，应该删除M之前的数字并且不是M. i尝试使用按键事件检查仅限数字，它可以工作，但我认为我必须将它与keyup组合用于上述条件。

i have a text field which should accept only numbers but i have few conditions, 1. when i press first number 'M' should be appended 2. when i press further numbers 'M' should stay at end. eg. 1M 12M 123M 1236M 3. when i press backspace the number before M should be deleted and not M. i tried using keypress event check for number only,it works but i think i will have to combine it with keyup for the above conditions.

推荐答案

看看这里：在jQuery中使用正则表达式 [ ^ ]并尝试更改代码满足您的需求。 Have a look here: Using regex with jQuery[^] and try to change the code to your needs.

function fn() { var element = document.getElementById("NumberInput"); element.value = ""; element.onkeydown = function (e) { if (element.value.length == 0) { element.value = "M"; } }; element.onkeyup = function (e) { if (e.keyCode == 8) { var Number = element.value; var caretPos = element.selectionStart; if (caretPos == element.value.length) { Number = Number.replace('M', ''); Number = Number.substring(0, Number.length - 1); element.value = Number + 'M'; } } else { var Number = element.value; Number = Number.replace('M', ''); element.value = Number + 'M'; } }; }

在body onload上调用它。如果你熟悉jquery，你就可以做到这一点。这是针对您的问题的纯JavaScript解决方案。希望这会有所帮助。

call this on body onload. if you familiar with jquery you can do this less no of lines. this is pure javascript solution for your problem. hope this helps.