Category: JavaScript Answers

Sometimes, we want to iterate through a map in JavaScript.

In this article, we’ll look at how to iterate through a map in JavaScript.

How to iterate through a map in JavaScript?

To iterate through a map in JavaScript, we can use a for-of loop.

For instance, we write

const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

for (const [key, value] of myMap.entries()) {
  console.log(key, value);
}

to create a map with the Map constructor.

Then we call set to add the key and value of a map entry.

Next, we use the entries method to return an array with arrays of key-value pairs in myMap.

And then we use a for-of loop to loop through each entry.

key is the key of the entry and value is the value.

Conclusion

To iterate through a map in JavaScript, we can use a for-of loop.

Sometimes, we want to fix ‘command not found: jest’ error in the command line.

In this article, we’ll look at how to fix ‘command not found: jest’ error in the command line.

How to fix ‘command not found: jest’ error in the command line?

To fix ‘command not found: jest’ error in the command line, we run npx.

To run jest, we run

npx jest

Then it’ll run without Jest being installed locally.

Conclusion

To fix ‘command not found: jest’ error in the command line, we run npx.

Sometimes, we want to pass an event object to a function in JavaScript.

In this article, we’ll look at how to pass an event object to a function in JavaScript.

How to pass an event object to a function in JavaScript?

To pass an event object to a function in JavaScript, we can use the addEventListener method.

For instance, we write

const onClick = (ev) => {
  ev.preventDefault();
  console.log("Hello World!");
};

document.getElementById("my_button").addEventListener("click", onClick);

to select the element with getElementById.

And then we add a click event listener to it with addEventListener.

We set the onClick function as the click event listener.

It takes the ev event object as its argument.

Conclusion

To pass an event object to a function in JavaScript, we can use the addEventListener method.

Sometimes, we want to convert JavaScript date object to ticks.

In this article, we’ll look at how to convert JavaScript date object to ticks.

How to convert JavaScript date object to ticks?

To convert JavaScript date object to ticks, we can use the date’s getTime method.

For instance, we write

const ticks = new Date().getTime();

to create a date object and call its getTime method to return the Unix timestamp of the datetime in milliseconds.

Conclusion

To convert JavaScript date object to ticks, we can use the date’s getTime method.

Sometimes, we want to enforce min. zoom level when using fitBounds with Google Maps v3 and JavaScript.

In this article, we’ll look at how to enforce min. zoom level when using fitBounds with Google Maps v3 and JavaScript.

How to enforce min. zoom level when using fitBounds with Google Maps v3 and JavaScript?

To enforce min. zoom level when using fitBounds with Google Maps v3 and JavaScript, we can set the minimum zoom level in the bounds_changed event handler.

For instance, we write

const zoomChangeBoundsListener = google.maps.event.addListener(
  map,
  "bounds_changed",
  (event) => {
    google.maps.event.removeListener(zoomChangeBoundsListener);
    map.setZoom(Math.min(15, map.getZoom()));
  }
);

map.fitBounds(zoomBounds);

to call addListener to listen to the bounds_changed event on the map.

In the event listener, we call map.setZoom to set the zoom level to 15 if the zoom level is below 15.

Otherwise, we use getZoom to return the zoom level and set that as the zoom level of the map.

Conclusion

To enforce min. zoom level when using fitBounds with Google Maps v3 and JavaScript, we can set the minimum zoom level in the bounds_changed event handler.