Time and date in JS - javascript

I'm creating simple web app that shows you what date and time is it now. It works good but i want to make it to be more dynamic so you can see time counting. What is best way to do this?
var hdate = document.getElementById('time');
var body = document.querySelector('body');
var bgM = document.getElementsByClassName('bgMorning')
var today = new Date();
var date = today.getFullYear()+'-'+(today.getMonth()+1)+'-'+today.getDate();
var time = today.getHours() + ":" + today.getMinutes() + ":" + today.getSeconds();
var dateTime = date+' '+time;
hdate.textContent = dateTime;

you could write your code inside an interval like this to update it every second.
setInterval(function(){
//write you code here to be executed every second
}, 1000);
you'll need to re-render your display element too. Use something like this
<html>
<p id="displayElement"></p>
<script>
//use this code inside your setInterval function so it re-renders every second
document.getElementById("displayElement").innerHTML = `<p>${time}</p>`;
</script>
</html>
let me know how that works!

You just need to call setInterval(func, interval_milliseconds).
Also try using template literals (e.g. ${hours}:${minutes}) to construct your strings in a more readable style.
Use let as opposed to var unless you need to support old versions of I.E.
let timeEl = document.getElementById('time');
let updateTimeEl = () => {
let today = new Date();
let date = `${today.getFullYear()}-${today.getMonth() + 1}-${today.getDate()}`;
let time = `${today.getHours()}:${today.getMinutes()}:${today.getSeconds()}`;
timeEl.textContent = `${date} ${time}`;
};
setInterval(updateTimeEl, 1000);
<div id="time"></div>

Try this.
function startTime() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
// add a zero in front of numbers<10
m = checkTime(m);
s = checkTime(s);
hdate.textContent = h + ":" + m + ":" + s;
// document.getElementById('time').innerHTML = h + ":" + m + ":" + s;
t = setTimeout(function() {
startTime()
}, 500);
}
startTime(); //it starts the timer
function checkTime(i) {
if (i < 10) {
i = "0" + i;
}
return i;
}

Not sure if your code is the best, but you can just wrap it in a setInterval.
setInterval(function(){
var hdate = document.getElementById('time');
var body = document.querySelector('body');
var bgM = document.getElementsByClassName('bgMorning')
var today = new Date();
var date = today.getFullYear()+'-'+(today.getMonth()+1)+'-'+today.getDate();
var time = today.getHours() + ":" + today.getMinutes() + ":" +
today.getSeconds();
var dateTime = date+' '+time;
console.log(dateTime)
}, 1000)
The second argument in the setIterval function is the interval that the code runs in miliseconds. So this will print to the console every second (1000ms -> 1s)

Related

Correctly Formatting Time for Document Title

I have the below code loaded in the head of a small HTML file. It is meant to grab the current time, convert it to 12H, add am or pm and then set this as the document title. This appears to work as I want, until the final line where I want it to run the function every 5 seconds so the document title updates dynamically. For whatever reason this isn't working and I can't figure out why. Can anyone assist?
function tConv24(time24) {
var ts = time24;
var H = +ts.substr(0, 2);
var h = (H % 12) || 12;
h = (h < 10)?("0"+h):h;
var ampm = H < 12 ? " am" : " pm";
ts = h + ts.substr(2, 3) + ampm;
return ts;
}
var today = new Date();
var currentTime = today.getHours() + ":" + today.getMinutes();
document.title = tConv24(currentTime);
setInterval(tConv24(currentTime), 5000);
Your logic seems fine, except that currentTime is only initialized once. So, the function tConv24 is being called each time with the same value. To correct, you need to make sure you always grab the latest date time by using the Date constructor:
function tConv24(time24) {
// function implementation
}
setInterval(function() {
var today = new Date();
var currentTime = today.getHours() + ":" + today.getMinutes();
document.title = tConv24(currentTime);
}, 5000);
Check this out:
let doc, bod, I, displayTime; // for use on other loads
addEventListener('load', ()=>{
doc = document; bod = doc.body;
I = id=>doc.getElementById(id);
displayTime = ()=>{
let dt = new Date, hr = dt.getHours(), mn = dt.getMinutes(), pm = 'am';
if(hr > 12){
hr -= 12; pm = 'pm';
}
if(mn.toString().length < 2)mn = '0'+mn;
return hr+':'+mn+pm;
}
const test = I('test');
test.textContent = displayTime();
setInterval(()=>{
test.textContent = displayTime();
}, 1000);
});
<div id='test'></div>

show real time clock on html using javascript

can someone help me with this code, I'm really bad using JS
I want to show only Brazil time in the application, regardless of where the user accesses the application.
<head>
<script>
function display_c() {
var refresh = 1000; // Refresh rate in milli seconds
mytime = setTimeout('display_ct()', refresh)
}
function display_ct() {
var strcount
var x = new Date().toLocaleString("en-US", {timeZone: "America/Sao_Paulo"});
var x1 = x.getMonth() + 1 + "/" + x.getDate() + "/" + x.getYear();
x1 = x1 + " - " + x.getHours( ) + ":" + x.getMinutes() + ":" + x.getSeconds();
document.getElementById('ct').innerHTML = x1;
tt = display_c();
}
</script>
</head>
<body onload=display_ct();>
<span id='ct' ></span>
</body>
Error
painel:48 Uncaught TypeError: x.getMonth is not a function
at display_ct (painel:48)
at onload (painel:57)
This code will do what you want. Your problem was that you used toLocaleString on your x variable and then tried to use the getMonth() method on it. However, that variable is no longer a date; when you use toLocaleString you turn it into a String. The local string, by default, is formatted almost how you like it. I only had to change a little bit to use the dash in between the date and time instead of the default comma.
var timeDisplay = document.getElementById("time");
function refreshTime() {
var dateString = new Date().toLocaleString("en-US", {timeZone: "America/Sao_Paulo"});
var formattedString = dateString.replace(", ", " - ");
timeDisplay.innerHTML = formattedString;
}
setInterval(refreshTime, 1000);
<p id="time"></p>
// Inside your Javascript file
function startTime() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
m = checkTime(m);
s = checkTime(s);
document.getElementById('txt').innerHTML =
h + ":" + m + ":" + s;
var t = setTimeout(startTime, 500);
}
function checkTime(i) {
if (i < 10) {i = "0" + i}; // add zero in front of numbers < 10
return i;
}
<!-- Inside your HTML file -->
<body onload="startTime()">
<div id="txt"></div>
</body>

Using jQuery.text() Causes Memory Leak

I am creating a single page application that will remain active and open for multiple days at a time in a browser. On this page I am displaying a timer in the top right corner. I have found however, that the way I am using the timer is leaking a small amount of memory.
https://jsfiddle.net/zbgonp84/
$(function(){
timer();
});
function timer(){
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
m = checkTime(m);
s = checkTime(s);
$("#timer").text(h + ":" + m + ":" + s);
var t = setTimeout(timer, 1000);
}
function checkTime(i) {
if (i < 10){
i = "0" + i;
}
return i;
}
I have recreated just the timer and the timer's div in a fiddle. If you open chrome's dev tools and record a time line, you can see that every second a new node is added to memory. If left for 24 hours, it will add a new node every second for the whole day and never gets collected.
I feel as if I am missing something fairly obvious as to why this is not being garbage collected, but what am I missing to unallocate the memory?
Create and substitute a reference to #timer element for calling jQuery() at each call to timer. Also, declare variable t outside of timer
$(function() {
const time = $("#timer");
var t;
timer();
function timer() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
m = checkTime(m);
s = checkTime(s);
time.text(h + ":" + m + ":" + s);
t = setTimeout(timer, 1000);
}
function checkTime(i) {
if (i < 10){
i = "0" + i;
}
return i;
}
});

How to print and update current time in jquery

I have the following code that displays the user's local time:
HTML
<h1 id="time"></h1>
Script
var d = new Date();
var hours = d.getHours();
var minutes = d.getMinutes();
var mins=new Array(9);
mins[0]="00";
mins[1]="01";
...
mins[59]="59";
var MinName = mins[d.getMinutes()];
document.getElementById('time').innerHTML = hours+":"+MinName;
How can I modify this to update automatically as time passes, without reloading the page?
Here you have a real simple solution:
setInterval(function() {
var date = new Date();
$('#time').html(
date.getHours() + ":" + date.getMinutes() + ":" + date.getSeconds()
);
}, 500);
You need to use setInterval http://www.w3schools.com/jsref/met_win_setinterval.asp
setInterval(function () {
var d = new Date();
var hours = d.getHours();
var minutes = d.getMinutes();
var mins=new Array(9);
mins[0]="00";
mins[1]="01";
...
mins[59]="59";
var MinName = mins[d.getMinutes()];
document.getElementById('time').innerHTML = hours+":"+MinName;
}, 1000);

How to show current time in JavaScript in the format HH:MM:SS?

How do I show the current time in the format HH:MM:SS?
You can use native function Date.toLocaleTimeString():
var d = new Date();
var n = d.toLocaleTimeString();
This will display e.g.:
"11:33:01"
MDN: Date toLocaleTimeString
var d = new Date();
var n = d.toLocaleTimeString();
alert("The time is: \n"+n);
function checkTime(i) {
if (i < 10) {
i = "0" + i;
}
return i;
}
function startTime() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
// add a zero in front of numbers<10
m = checkTime(m);
s = checkTime(s);
document.getElementById('time').innerHTML = h + ":" + m + ":" + s;
t = setTimeout(function() {
startTime()
}, 500);
}
startTime();
<div id="time"></div>
DEMO using javaScript only
Update
Updated Demo
(function () {
function checkTime(i) {
return (i < 10) ? "0" + i : i;
}
function startTime() {
var today = new Date(),
h = checkTime(today.getHours()),
m = checkTime(today.getMinutes()),
s = checkTime(today.getSeconds());
document.getElementById('time').innerHTML = h + ":" + m + ":" + s;
t = setTimeout(function () {
startTime()
}, 500);
}
startTime();
})();
You can do this in Javascript.
var time = new Date();
console.log(time.getHours() + ":" + time.getMinutes() + ":" + time.getSeconds());
At present it returns 15:5:18. Note that if any of the values are less than 10, they will display using only one digit, not two.
Check this in JSFiddle
Updates:
For prefixed 0's try
var time = new Date();
console.log(
("0" + time.getHours()).slice(-2) + ":" +
("0" + time.getMinutes()).slice(-2) + ":" +
("0" + time.getSeconds()).slice(-2));
You can use moment.js to do this.
var now = new moment();
console.log(now.format("HH:mm:ss"));
Outputs:
16:30:03
new Date().toTimeString().slice(0,8)
Note that toLocaleTimeString() might return something like 9:00:00 AM.
Use this way:
var d = new Date();
localtime = d.toLocaleTimeString('en-US', { hour12: false });
Result: 18:56:31
function realtime() {
let time = moment().format('h:mm:ss a');
document.getElementById('time').innerHTML = time;
setInterval(() => {
time = moment().format('h:mm:ss a');
document.getElementById('time').innerHTML = time;
}, 1000)
}
realtime();
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.1/moment.min.js"></script>
<div id="time"></div>
A very simple way using moment.js and setInterval.
setInterval(() => {
moment().format('h:mm:ss a');
}, 1000)
Sample output
Using setInterval() set to 1000ms or 1 second, the output will refresh every 1 second.
3:25:50 pm
This is how I use this method on one of my side projects.
setInterval(() => {
this.time = this.shared.time;
}, 1000)
Maybe you're wondering if using setInterval() would cause some performance issues.
Is setInterval CPU intensive?
I don't think setInterval is inherently going to cause you significant performance problems. I suspect the reputation may come from an earlier era, when CPUs were less powerful. ... - lonesomeday
No, setInterval is not CPU intensive in and of itself. If you have a lot of intervals running on very short cycles (or a very complex operation running on a moderately long interval), then that can easily become CPU intensive, depending upon exactly what your intervals are doing and how frequently they are doing it. ... - aroth
But in general, using setInterval really like a lot on your site may slow down things. 20 simultaneously running intervals with more or less heavy work will affect the show. And then again.. you really can mess up any part I guess that is not a problem of setInterval. ... - jAndy
new Date().toLocaleTimeString('it-IT')
The it-IT locale happens to pad the hour if needed and omits PM or AM 01:33:01
Compact clock function:
setInterval(function() {
let d = new Date()
console.log(`${d.getHours()}:${d.getMinutes()}:${d.getSeconds()}`)
}, 1000);
This code will output current time in HH:MM:SS format in console, it takes into account GMT timezones.
var currentTime = Date.now()
var GMT = -(new Date()).getTimezoneOffset()/60;
var totalSeconds = Math.floor(currentTime/1000);
seconds = ('0' + totalSeconds % 60).slice(-2);
var totalMinutes = Math.floor(totalSeconds/60);
minutes = ('0' + totalMinutes % 60).slice(-2);
var totalHours = Math.floor(totalMinutes/60);
hours = ('0' + (totalHours+GMT) % 24).slice(-2);
var timeDisplay = hours + ":" + minutes + ":" + seconds;
console.log(timeDisplay);
//Output is: 11:16:55
This is an example of how to set time in a div(only_time) using javascript.
function date_time() {
var date = new Date();
var am_pm = "AM";
var hour = date.getHours();
if(hour>=12){
am_pm = "PM";
}
if (hour == 0) {
hour = 12;
}
if(hour>12){
hour = hour - 12;
}
if(hour<10){
hour = "0"+hour;
}
var minute = date.getMinutes();
if (minute<10){
minute = "0"+minute;
}
var sec = date.getSeconds();
if(sec<10){
sec = "0"+sec;
}
document.getElementById("time").innerHTML = hour+":"+minute+":"+sec+" "+am_pm;
}
setInterval(date_time,500);
<per>
<div class="date" id="time"></div>
</per>
new Date().toLocaleTimeString()
function realtime() {
let time = moment().format('hh:mm:ss.SS a').replace("m", "");
document.getElementById('time').innerHTML = time;
setInterval(() => {
time = moment().format('hh:mm:ss.SS A');
document.getElementById('time').innerHTML = time;
}, 0)
}
realtime();
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.1/moment.min.js"></script>
<div id="time"></div>
Use
Date.toLocaleTimeString()
// Depending on timezone, your results will vary
const event = new Date('August 19, 1975 23:15:30 GMT+00:00');
console.log(event.toLocaleTimeString('en-US'));
// expected output: 1:15:30 AM
console.log(event.toLocaleTimeString('it-IT'));
// expected output: 01:15:30
console.log(event.toLocaleTimeString('ar-EG'));
// expected output: ١٢:١٥:٣٠
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