Category: JavaScript

Sometimes, we want to create JavaScript array (JSON format) dynamically.

In this article, we’ll look at how to create JavaScript array (JSON format) dynamically.

How to create JavaScript array (JSON format) dynamically?

To create JavaScript array (JSON format) dynamically, we call the array push method.

For instance, we write

const students = [];
const obj = {
  firstName: name,
  lastMame: name,
  age: age,
};
students .push(obj);

to call students.push with obj to add the obj object as the last entry of the students array.

Conclusions

To create JavaScript array (JSON format) dynamically, we call the array push method.

Sometimes, we want to start the week on Monday with isoWeekday() with JavaScript.

In this article, we’ll look at how to start the week on Monday with isoWeekday() with JavaScript.

How to start the week on Monday with isoWeekday() with JavaScript?

To start the week on Monday with isoWeekday() with JavaScript, we call startOf with 'week' before calling isoWeekday.

For instance, w write

const begin = moment(date).startOf("week").isoWeekday(1);

to call startOf on the moment object to get the start of the week.

And then we call isoWeekday with 1 to set the start of the week to Monday.

Conclusion

To start the week on Monday with isoWeekday() with JavaScript, we call startOf with 'week' before calling isoWeekday.

Sometimes, we want to detect if a user is already logged in Firebase with JavaScript.

In this article, we’ll look at how to detect if a user is already logged in Firebase with JavaScript.

How to detect if a user is already logged in Firebase with JavaScript?

To detect if a user is already logged in Firebase with JavaScript, we can call the onAuthStateChanged method.

For instance, we write

firebase.auth().onAuthStateChanged((user) => {
  if (user) {
    // ...
  } else {
    // ...
  }
});

to call onAuthStateChanged with a callback that checks if the user is set.

If user is set, then the user is logged in.

Otherwise, the user isn’t logged in.

Conclusion

To detect if a user is already logged in Firebase with JavaScript, we can call the onAuthStateChanged method.

Sometimes, we want to use regex to get string between curly braces with JavaScript.

In this article, we’ll look at how to use regex to get string between curly braces with JavaScript.

How to use regex to get string between curly braces with JavaScript?

To use regex to get string between curly braces with JavaScript, we can use the /{(.*?)}/ regex.

For instance, we write

const re = /{(.*?)}/;

to use the re regex to get the string between curly braces.

We use (.*?) inside the curly braces to match anything inside the curly braces.

Conclusion

To use regex to get string between curly braces with JavaScript, we can use the /{(.*?)}/ regex.