如何将光标聚焦在文本框上? [英] how to focus cursor on textbox?

问题描述

这是我在javascript中用于验证textBox是否为空的代码，
它可以正常工作，但是在验证之后它会跳转到下一个文本框，我希望我的光标指向同一个文本框，直到他输入正确的输入为止.

This is my code in javascript to validate whether the textBox is empty or not,
it works fine but after validating it jumps to next textbox, I want my cursor to be pointing on the same textBox untill he enters the correct input.

function trainNoName(txt)
{
  var trainNo=txt.value;
  if(trainNo=="")
  {
  alert(txt.name+" Field Can''t be empty");
  document.getElementById("stFrm").focus();
  }
}

//我在最后一行中使用了focus()，但它不起作用.

//i have used focus() in my last line but its not working.

推荐答案

尝试以下操作:-

Try this:-

function trainNoName(txt)
{
  var txtTN=document.getElementById(txt);
  var trainNo=txtTN.value;
  if(trainNo==''''){
  alert(''Train No Field Cannot be empty'');
  document.getElementById(txtTN).focus();
  }
}

我希望这能解决问题.

I hope this will work.

用你的思想.


使用if()... else....

Use your mind.


use if()...else....

我将假定txt是输入，因为您正在访问txt.value和txt.name:

I''ll assume that txt is the input, since you are accessing txt.value and txt.name:

function trainNoName(txt) {
   var trainNo=txt.value;
   if(trainNo=="") {
      alert(txt.name+" Field Can't be empty");
      txt.focus();
   }
}

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