如何防止'0'成为文本框中输入的第一个字符(How to prevent '0' to be the first char entered in a textb

如何防止'0'成为文本框中输入的第一个字符(How to prevent '0' to be the first char entered in a textbox)

如何轻松地防止0成为使用JavaScript在文本框中输入的第一个字符？ 我想要像.Net OnKeyDown()这样的东西。 当用户按下0键以防止第一个字符时

e.Handled = true;

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为什么这不起作用？

function PreventFirstCharZero() { var TB = document.getElementById("idbox").value; var TextLength = TB.value.length; if (48 == event.keyCode && 0 == TextLength) { event.preventDefault(); } }

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这不起作用

function PreventFirstCharZero() { if ('0' == document.getElementById("idbox")[0].value) { event.preventDefault(); } }

How to easily prevent 0 from being the first char entered in a textbox with JavaScript? I want something like the .Net OnKeyDown(). When the user presses 0 key for the first char to be prevented

e.Handled = true;

---

Why doesnt this work?

function PreventFirstCharZero() { var TB = document.getElementById("idbox").value; var TextLength = TB.value.length; if (48 == event.keyCode && 0 == TextLength) { event.preventDefault(); } }

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This doesn't work

function PreventFirstCharZero() { if ('0' == document.getElementById("idbox")[0].value) { event.preventDefault(); } }

最满意答案

尝试这个！

$("#input").on("keypress keyup",function(){ if($(this).val() == '0'){ $(this).val(''); } });

的jsfiddle

try this!

$("#input").on("keypress keyup",function(){ if($(this).val() == '0'){ $(this).val(''); } });

jsfiddle