console.log
'1' after 1 second,
'2' after 2 seconds and
'3' after 3 seconds after start of the program.
The delay parameter only guarantees that your callback will not execute before that time has elapsed. Other queued tasks or operations could delay it further than the specified time.
const startTime = process.hrtime();
console.log('startTime: ', startTime);
for (let i = 1; i < 4; i++) {
setTimeout(() => {
console.log('Message ' + i + ' ', process.hrtime());
}, i * 1000);
}
startTime: [ 20341, 488209050 ]
Message 1 [ 20342, 499922394 ]
Message 2 [ 20343, 498388755 ]
Message 3 [ 20344, 498487014 ]
console.log('startTime: ', startTime);
for (let i = 1; i < 4; i++) {
setTimeout(() => {
console.log('Message ' + i + ' ', process.hrtime(startTime));
}, i * 1000);
}
startTime: [ 20482, 505385747 ]
Message 1 [ 1, 13938178 ]
Message 2 [ 2, 13741552 ]
Message 3 [ 3, 13861540 ]
for (let i = 1; i < 4; i++) {
setTimeout(() => {
console.log('Message ' + i + ' ', process.uptime());
}, i * 1000);
}
Message 1 1.10126115
Message 2 2.102194643
Message 3 3.102512365
const startTime = process.hrtime();
console.log('startTime: ', startTime);
let i = 1;
const interval = setInterval(() => {
console.log('Message ' + i + ' ', process.hrtime());
i++;
if (i > 3) {
clearInterval(interval);
}
}, 1000);
startTime: [ 21511, 206821155 ]
Message 1 [ 21512, 217929990 ]
Message 2 [ 21513, 218730640 ]
Message 3 [ 21514, 218790140 ]
const startTime = process.hrtime();
console.log('startTime: ', startTime);
let i = 1;
const interval = setInterval(() => {
console.log('Message ' + i + ' ', process.hrtime(startTime));
i++;
if (i > 3) {
clearInterval(interval);
}
}, 1000);
startTime: [ 21356, 295521886 ] Message 1 [ 1, 10849822 ] Message 2 [ 2, 11730624 ] Message 3 [ 3, 14871246 ]
let i = 1;
const interval = setInterval(() => {
console.log('Message ' + i + ' ', process.uptime());
i++;
if (i > 3) {
clearInterval(interval);
}
}, 1000);
Message 1 1.094841971
Message 2 2.09636721
Message 3 3.098306832
OpenAi: How we can make delay more precise?
To achieve a more precise delay in JavaScript, especially in environments like Node.js where setTimeout and setInterval may not always guarantee exact timing due to the event loop's nature, you can use process.hrtime() for high-resolution time measurements and combine it with a busy-wait loop (also known as spin-waiting or spinning) to achieve more precise timing. Here's how you can implement it:
Output
Message 1 1.104189437
Message 2 2.110839667
Message 3 3.111090676
Explanation:
Using process.hrtime(): This provides a high-resolution timestamp as an array of [seconds, nanoseconds].
Calculating Target Time: start captures the current time using process.hrtime(), and target calculates the precise future time to resolve the promise based on the specified ms delay.
Spin-Wait Loop: Inside preciseDelay, spinWait checks the current time using process.hrtime() in a loop (setImmediate for Node.js environment), until the current time exceeds or meets the target time.
Resolution: Once the target time is reached, resolve() is called to complete the promise.
Benefits of this approach:
High Precision: Using process.hrtime() allows for high-resolution timing, which is crucial for precise measurements.
Minimizing Variability: By using a spin-wait loop with setImmediate, you reduce the variability introduced by the event loop, improving the precision of the delay.
Considerations:
CPU Usage: Spin-waiting can consume CPU cycles while waiting, so it's essential to balance precision with efficiency, depending on your application's needs.
Node.js Environment: This approach is suitable for Node.js environments where setImmediate is available. For browsers, requestAnimationFrame or Performance.now() might be used instead.
By combining process.hrtime() for precise time measurements and a spin-wait loop, you can achieve more accurate and reliable delays in your JavaScript applications.