Category: JavaScript

Sometimes, we want to use promise function inside JavaScript array map.

In this article, we’ll look at how to use promise function inside JavaScript array map.

How to use promise function inside JavaScript array map?

To use promise function inside JavaScript array map, we use the Promise.all function.

For instance, we write

const mappedArray = await Promise.all(
  array.map(async (p) => {
    const i = await getPromise(p);
    return i.item;
  })
);

to call array.map with an async function that returns a promise with i.item as its resolve value.

map returns an array of promises with their resolve values.

Then we use Promise.all to run all the promises and get their resolve values with await.

Conclusion

To use promise function inside JavaScript array map, we use the Promise.all function.

Sometimes, we want to export all functions from a file in JavaScript.

In this article, we’ll look at how to export all functions from a file in JavaScript.

How to export all functions from a file in JavaScript?

To export all functions from a file in JavaScript, we can use the export keyword.

For instance, we write

export const foo = () => {
  // ...
};
export const bar = () => {
  // ...
};
export const baz = (value) => {
  // ...
};

to export the foo, bar, and baz functions by adding export before the function expression.

Conclusion

To export all functions from a file in JavaScript, we can use the export keyword.

Sometimes, we want to add ID’s to Google map markers with JavaScript.

In this article, we’ll look at how to add ID’s to Google map markers with JavaScript.

How to add ID’s to Google map markers with JavaScript?

To add ID’s to Google map markers with JavaScript, we can add custom attributes.

For instance, we write

const marker = new google.maps.Marker({
  map,
  position,
  storeId: id,
});

const storeId = marker.get("storeId");

to create a marker with the Marker constructor.

We add the storeId custom attribute.

Then we call marker.get with the attribute name string to get the attribute value.

Conclusion

To add ID’s to Google map markers with JavaScript, we can add custom attributes.

Sometimes, we want to check if input is number or letter JavaScript.

In this article, we’ll look at how to check if input is number or letter JavaScript.

How to check if input is number or letter JavaScript?

To check if input is number or letter JavaScript, we can use the isNaN function.

For instance, we write

const checkInput = () => {
  const x = document.forms.myForm.age.value;
  if (isNaN(x)) {
    alert("Must input numbers");
    return false;
  }
};

to define the checkInput function.

In it, we get the value from the input with name age in the form with name myForm with document.forms.myForm.age.value.

We check if the value isn’t a number with isNaN.

If it’s true, then x isn’t a number.

Conclusion

To check if input is number or letter JavaScript, we can use the isNaN function.