问题
I am sending the request via AJAX to the server.
I want to send the response to the AJAX call back whenever an error occurs.
So for that in callback function I am writing this return code inside the error block. res.end('{"msg" : "Some error occurred", "status" : 700}');
And with status I am throwing an alert on UI with this message.
But whenever the code fails or some errors occurs the console do writes the console error in console but also the server stops and failed to reload the page again and I have to run npm start again. But it don't return the msg and status back to AJAX call as final response.
How to handle the code to achieve this?
Means whenever any error occurs I want to send an error alert on UI instead of full blockage of the server and webpage.
router.route('/addTasks-approve').get(function(req, res) {
User.updateMany({'Addtasks.commonID':req.query.id},
{$set: {"Addtasks.$.width" :'250px',
"Addtasks.$.height" :'32px',
"Addtasks.$.background" :'linear-gradient(45deg, #0f3443, #34e89e)',
"Addtasks.$.border_radius" :'10px / 5px',
"Addtasks.$.status" :req.query.text}},
function (error, success) {
if (!error) {
console.log("Approved color set!");
User.findOne({tag:'Admin','Addtasks.commonID':req.query.id},function (error, dataAdmin) {
if (error) {
console.log("error = "+ error);
res.end('{"msg" : "Some error occurred", "status" : 700}');
}
else {
dataAdmin.Addtasks.forEach(element => {
if(element.commonID == req.query.id)
{
User.findOneAndUpdate({tag:'Client','Addtasks.commonID':req.query.id},
{$push: {'Addtasks.$.Bigpaths4Clients':{$each : element.Bigpaths4Clients}},
$set: {"Addtasks.$.background" :'linear-gradient(45deg, #1E6305, #BDFF00)',
"Addtasks.$.status" :'Done'}},
function (error, data) {
if (error) {
console.log("error = "+ error);
res.end('{"msg" : "Unable to add the Task", "status" : 700}');
}
else {
console.log("Addtasks added to Client's dashboard succesfully");
sendMails2Client(data.email, element.topic, 'In Progress', 'Done');
sendMails2User(dataAdmin.email, element.topic, 'Done', 'Approved');
User.findOne({tag:'Admin','Addtasks.commonID':req.query.id},function (error, dataWriter) {
if (error) {
console.log("error = "+ error);
res.end('{"msg" : "Some error occurred", "status" : 700}');
}
else {
sendMails2User(dataWriter.email, element.topic, 'Done', 'Approved');
res.end('{"success" : "success", "status" : 200}');
}
})
}
})
}
});
}
});
}
else {
res.end('{"msg" : "Unable to set the status and color for Approved", "status" : 700}');
}
});
});
来源：https://stackoverflow.com/questions/65809059/how-to-send-an-error-alert-in-ui-whenever-an-error-occurs-on-server-side-in-node