We're trying to make an application that pairs users in a database every Wednesday and Friday. How is done in Meteor?
So in the server code I was thinking of putting this in a timedserver.js file
boolean hasMatched = false;
boolean isWednesday = false;
while(true){
if (day != Wednesday) isWednesday = false;
if (day == Wednesday){
matchUsers()
Wednesday = true;
}
setTimeOut(5 HOURS)
}
Is this how it should be approached? I'm not sure how to have continually running server code. Where do we put this code?
I would propose to use Meteor.setInterval() instead of using an infinite while-loop, and why not using an interval of 24 hours instead of 5?
Then you can check the weekday of the current date, e.g. with moment.js, and if it's wednesday or friday, run your code, at best asynchronously and non-blocking the interval.
I probably wouldn't use a while loop for something like this.
One package comes to mind though: synced-cron. It looks like it uses "Parsers" and there is quite a bit flexibility there.
Something like this would probably work:
SyncedCron.add({
name: 'Crunch some important numbers for the marketing department',
schedule: function(parser) {
// parser is a later.parse object
return parser.text('every Wednesday');
},
job: function() {
var matchedUsers = matchUsers();
return matchedUsers;
}
});
I've never uses this package, but I believe this code would fire every Wednesday.
May be using cron job will be better solution?
Related
I know javascript is not the best way to go about this. I know that I would have to have the browser up and always running. I would normally do something with Python. This was a specific requests of me and i'm not very proficient with javascript. That being said.
I want the user to be able to set a time using inputs. Once these inputs have been set I want the browser to check for the time specified. Once the time occurs I want it to execute a command.
Her is what I have so far:
<html>
<body>
<p>Enter Time to start dashboard</p>
<p>Hour</p>
<input id="strthour">
<p>Minute</p>
<input id="strtmin">
<button onclick="setTime()">Submit</button>
<script>
var hr = 06; //default time of 6am to run
var mn = 00;
function setTime() {
hr = strthour.value;
mn = strtmin.value;
}
window.setInterval(function(){ // Set interval for checking
alert(hr+mn);
var date = new Date(); // Create a Date object to find out what time it is
if(date.getHours() === hr && date.getMinutes() === mn && date.getSeconds() === 0){ // Check the time
alert("it worked")
}
}, 5000); // Repeat every 60000 milliseconds (1 minute)
</script>
</body>
</html>
I am able to change the global variables, but I am unable to get window.setInterval to recognize the changes. Any advice?
Here is a link to a JSFiddle I made.
There are several issues with your code, which various people have pointed out.
Walker Randolph Smith correctly notes that date.GetHours() and date.getMinutes() will both return numbers, while the values returned from strthour.value and strtmin.value will be strings. When JavaScript compares these two, it will always evaluate to false. To fix this, try running the user input through parseInt, as in hr = parseInt(strthour.value, 10);. The 10 is important because it tells parseInt to create a number of base 10 (you don't need to know what that means, just make sure to include the 10).
Your need for the seconds to match is probably unnecessary, and does not match up with the interval you chose. TheMintyMate made this correction in their code snippet by simply removing the comparison for seconds. If you really need to make sure the seconds match up perfectly, pick an interval of less than 1000 milliseconds, so you know it is going to check at least once every second, guaranteeing that you will run the check on that 0th second of the desired time.
You could run into some trouble with single digit minutes if you try to compare them as strings, rather than converting to numbers as recommended in point 1. The .getMinutes() method will return a single digit 0 for a time like 6:00, while your example is implicitly prompting the user to enter in two digits for that same time. Again, you can avoid this issue entirely by using parseInt as recommended in point #1.
I do have to throw in a plug for using Cron jobs for running tasks on a known schedule like this. I know you said the user requested JS in this case, so they may not apply for this specific situation. Since you didn't mention Cron jobs though, I have to include them here to make sure you and future readers are aware of them, because they are designed for exactly this situation of running a task on an automated schedule.
Good luck!
You are not correctly referring to the inputs, and you also have a syntax error with your alert. Below is my suggested fix (working):
<p>Enter Time to start dashboard</p>
<p>Hour</p>
<input id="strthour">
<p>Minute</p>
<input id="strtmin">
<button onclick="setTime()">Submit</button>
<script>
var hr = 0;
var mn = 0;
function setTime() {
hr = parseInt(document.getElementById("strthour").value);
mn = parseInt(document.getElementById("strtmin").value);
console.log("set time: "+hr+":"+mn);
}
setInterval(function(){
var date = new Date();
if(date.getHours() == hr && date.getMinutes() == mn){ // using == not ===
alert("it worked");
}
}, 10000);
</script>
Note: You should also parseInt() the values to ensure they are valid numbers.
if(date.getHours() === hr && date.getMinutes() === mn && date.getSeconds() === 0){ // Check the time
alert("it worked")
}
This will compare a string to an int and always be false.
either perform parseInt(date.getHours()) or use ==
It's not because setInterval doesn't recognize the change, you actually don't modify the values.
If you open the javascript console on jsfiddle page you'll see "Uncaught ReferenceError: setTime is not defined".
It will work if you define you setTime like this:
window.setTime = function() {
hr = strthour.value;
mn = strtmin.value;
}
This is because JSFiddle doesn't run your code directly, but wraps into
<script type='text/javascript'>//<![CDATA[
window.onload=function(){
... // you code here }
}//]]>
Here is a modified JSFiddle which just "it worked" for me.
Update - some notes, as mentioned in other answers:
The use of '===' is also an issue, hr/mn are strings, so you need '==' or convert hr/mn to integers
Expression like strthour.value in setTime works in JSFiddle. I am not really sure why, but it works. In the "real world" it should be something like document.getElementById("strthour").value
Update 2 - why does strthour.value work (vs document.getElementById("strthour").value)?
This was actually a surprise for me, but it looks like all major browsers put all elements with id into window object. More than that, it is actually a part of the HTML standard (although it is not recommended to use this feature):
6.2.4 Named access on the Window object
window[name]
Returns the indicated element or collection of elements.
As a general rule, relying on this will lead to brittle code. Which IDs end up mapping to this API can vary over time, as new features are added to the Web platform, for example. Instead of this, use document.getElementById() or document.querySelector().
References:
HTML 5.1 - 6.2.4 Named access on the Window object
Do DOM tree elements with ids become global variables?
Why don't we just use element IDs as identifiers in JavaScript?
I think you should use ">=" operator, because you don't know if it's gonna be EXACTLY that time.
I have a list of dates in an array(for now we can say that the dates are sorted). I want to have a script execute when the date matches a date in the array. My issue is figuring how to make this work on its own. I would like to have a server somehow act like an alarm clock that can run a script for a scheduled date and time. If anyone could help with suggestions to make this work I would appreciate it.
set date >>> if (currentDate == set date) >>> run script for the respective data
Please ask if you need clarification.
The way to do this with parse is a class with a date attribute. Create one object per date in your array of dates (they needn't be sorted).
Create a scheduled job that upon running, query's the class for the first date equal to the current date. If one is found, do whatever you want to do when an alarm is triggered.
So, something like...
Parse.Cloud.job("checkStatus", function(request, status) {
var today = new Date();
today.setHours(0, 0, 0, 0);
var tomorrow = new Date(today);
tomorrow.setDate(tomorrow.getDate() + 1);
var query = new Parse.Query("MyAlarmClass");
query.greaterThanOrEqualTo('theDateAttribute', today);
query.lessThan('theDateAttribute', tomorrow);
return query.first().then(function(anAlarm) {
if (anAlarm) {
// do whatever should be done on the alarm
} else {
// do nothing
}
}).then(function() {
status.success();
}, function(error) {
status.error(JSON.stringify(error));
});
});
Schedule this to run at least twice per day (or faster than whatever resolution you need on the alarms).
I have to calculate X working days before a date in javascript. I have an array of holidays, how can I do this?
I can make a while loop with my date and change it to the previous day and check if it's a business day then increment my variable but is it a good way to do this?
In normal languages you could easily solve this with a hashset. It has vary fast look up times, and random access.
However, Javascript isn't like all the other children. So it has it's own special way of doing this. The easiest way is just an object.
var holidays = {
1:true,
7:true,
18:true
}
I use days since newyear, but there isn't anything wrong with using a date or something else.
Then you can make a little helper function:
var checkDate = function(value){
return holidays [value] === true;
};
Then you just do checkDate(dayOfYear) and it will return true or false if it's a holiday. Then you can easily do
//This is more pseudocode than javascript, since I haven't done javascript in years
while checkDate(--dayOfYear === true)
previousBussinesDay = dayOfYear;
Or something similar to find the actual day.
I'm trying to get a video feed to only display on Thursdays between 7PM and 8PM because that's when the live feed is playing. For reasons I'll not go into, I'm not allowed to have it up at any other time. Since I'm new to JavaScript I'm sure I'm doing something wrong, but from what I've been able to learn this is what I've got.
var hour = getHours()
var day = getDay()
document.onload=function timechange() {
if day==4 && hour>19 && hour<21
document.getElementById(livefeed).innerHTML =
"Text one"
else
document.getElementById(livefeed).innerHTML =
"Text two"
}
This is example text obviously but the majority of the content will change on the page. Do I have to add some sort of function in my HTML page to make this work?
For the simple version, that's almost that. getDay() and getHours() are defined on the Date class:
function shouldShowVideo() {
var currentDate = new Date(),
currentDay = currentDate.getDay(),
currentHour = currentDate.getHours();
return (currentDay == 4 && currentHour > 19 && currentHour < 20);
}
if (shouldShowVideo()) {
// do something
} else {
// do something else
}
There is one big problem with this approach though. Because you do it in JS, the video will be loaded on your page, no matter what (so people could potentially get the link to it).
Also, because you are executing your JS after the onload event fired, there could be a few seconds where the video will be displayed. What you can do to improve this is run this code on DOM Ready event instead (here is the jQuery helper: http://api.jquery.com/ready/).
Your best option would still be to move this logic on the server. That way, you don't have to worry about all this: no JS involved.
I have a couple questions about javascript:
Does javascript have the capability to identify a filename with a timestamp as a name?
Similar to the Perl code below utilizing the POSIX module?
my $filepath = sprintf("/path/to/file%s.JSON",strftime("%y%m%d",localtime));
this is just an example. I would like to find file in format yy/mm/dd/hh/min
For example say I want to find a file with the name 12_11_03_15:15.json how can I do this with javascript.
Say I create a function that I want to trigger every 15 minutes to read the file how is this possible with javascript? I looked at setInterval() but that won't work because it is dependent on when the browser is launched. Is it possible to schedule a function to execute every hh:00, hh:15, hh:30, hh:45?
Thank you very much in advance.
You can use the Date class to get information about the current time.
To schedule a function to run at a certain time, setInterval() is indeed the best choice. It seems like what you're really looking for is a way to find out when to start the first interval such that it will fall on a quarter-hour. For that, you should again use Date to get the current time and subtract it from the next quarter-hour; you can use the resulting value with setTimeout to time the start of the first interval.
Here's an example: http://jsfiddle.net/GSF6C/3/
var nextQuarterHour = new Date();
nextQuarterHour.setMilliseconds(0);
nextQuarterHour.setSeconds(0);
do {
nextQuarterHour.setMinutes(nextQuarterHour.getMinutes() + 1);
} while (nextQuarterHour.getMinutes() % 15)
var millisecondsToNextQuarterHour = nextQuarterHour.getTime() - Date.now();
document.write(millisecondsToNextQuarterHour);
setTimeout(function () {
alert("Ding!");
setInterval(function () { alert("Dong!"); }, 15 * 60 * 1000);
}, millisecondsToNextQuarterHour);