javascript检查Node Js req.body内容后未提交HTML表单

Question

I got a problem, when my html Form submit, Node Js app.post{} will get correct value. However, when I use onsubmit in the form, and check value before submit. Then Node Js app.post req.body will display undefinded.

Original code: html:

<form id="formLogin" role="form" action="/loginprocess" method="POST">
  <input id="textEmail" name="username">
  <input id="textPwd" name="pwd">
  <button type="submit" id="btnLogin">login</button>
</form>

node.js:

var express = require('express');
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({     
  extended: true
}));

app.post('/loginprocess', function(req, res) {

    var username = req.body.username;
    var pwd = req.body.pwd;

    console.log("username=" + username);  //correct value
    console.log("pwd=" + pwd);            //correct value


});

however I want check value that input in form then submit, therefore, I update the form code like below:

html:

<form id="formLogin" role="form" action="/loginprocess" method="POST" onsubmit="return checkLoginInfo()">
  <input id="textEmail" name="username">
  <input id="textPwd" name="pwd">
  <button type="submit" id="btnLogin">login</button>
</form>

<script type="text/javascript">
function checkLoginInfo() {
    var username = document.getElementById("textEmail").value;
    var pwd = document.getElementById("textPwd").value;

    if ((username.length > 0) && (pwd.length > 0)) {
      console.log("yes");
     } else {
      console.log("no");
      return false;
     }
}
</script>

my node js:

var express = require('express');
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({     
  extended: true
}));

app.post('/loginprocess', function(req, res) {

    var username = req.body.username;
    var pwd = req.body.pwd;

    console.log("username=" + username);  //undefined
    console.log("pwd=" + pwd);            //undefined


});

Answer 1

Updated.

Since you have updated the question, i would suggest you this:

onsubmit="return checkLoginInfo(this)"  <!-- pass the form here -->

Now in the js function:

function checkLoginInfo(frm) { // <----get the form here
  var username = document.getElementById("textEmail").value;
  var pwd = document.getElementById("textPwd").value;

  if ((username.length > 0) && (pwd.length > 0)) {
    console.log("yes");
    frm.submit(); // <-----if valid just submit it here.
  } else {
    console.log("no");
    return false;
  }
}

Answer 2

If your username and password are correct your function checklogin (in the client js code ) doesn't return anything you'll have to add a return in it

and also add an id to your html inputs ( username and password )