Category: JavaScript Answers

Sometimes, we want to fill a JavaScript object literal with many static key/value pairs efficiently.

In this article, we’ll look at how to fill a JavaScript object literal with many static key/value pairs efficiently.

How to fill a JavaScript object literal with many static key/value pairs efficiently?

To fill a JavaScript object literal with many static key/value pairs efficiently, we create a map.

For instance, we write

const map = new Map([
  ["key1", "value1"],
  ["key2", "value2"],
]);
const value = map.get("key1");

to call the Map constructor with an array of key-value pair arrays to create a map.

Then we get the value by the get with 'key1'.

Conclusion

To fill a JavaScript object literal with many static key/value pairs efficiently, we create a map.

Sometimes, we want to open generated PDF using jspdf in new window with JavaScript.

In this article, we’ll look at how to open generated PDF using jspdf in new window with JavaScript.

How to open generated PDF using jspdf in new window with JavaScript?

To open generated PDF using jspdf in new window with JavaScript, we call the doc.output method.

For instance, we write

doc.output('dataurlnewwindow');

to open the PDF doc in a new window.

We can also write

const string = doc.output("datauristring");
const x = window.open();
x.document.open();
x.document.location = string;

to call output with 'datauristring' to return the base64 string URL version of the PDF.

Then we call window.open to open a new window.

And then we call document.open to open the document.

Finally we set document.location to the URL string to show the PDF.

Conclusion

To open generated PDF using jspdf in new window with JavaScript, we call the doc.output method.

Sometimes, we want to reverse a string in JavaScript.

In this article, we’ll look at how to reverse a string in JavaScript.

How to reverse a string in JavaScript?

To reverse a string in JavaScript, we use the string split and array reverse and join methods.

For instance, we write

const reversedStr = str.split("").reverse().join("");

to call str.split to split the string into an array of characters.

Then we call reverse to return a reversed version of the array.

And then we call join to combine the characters in the reversed array and return the string.

Conclusion

To reverse a string in JavaScript, we use the string split and array reverse and join methods.

Sometimes, we want to find the number of occurrences a given value has in an array with JavaScript.

In this article, we’ll look at how to find the number of occurrences a given value has in an array with JavaScript.

How to find the number of occurrences a given value has in an array with JavaScript?

To find the number of occurrences a given value has in an array with JavaScript, we use the array filter method.

For instance, we write

const dataset = [2, 2, 4, 2, 6, 4, 7, 8];
const search = 2;
const occurrences = dataset.filter((val) => {
  return val === search;
}).length;
console.log(occurrences);

to call datset.filter with a callback that checks if val in dataset is the same as search and return an array where all the values are equal to search.

Then we get the length property to get the number of items equal to search.

Conclusion

To find the number of occurrences a given value has in an array with JavaScript, we use the array filter method.

Sometimes, we want to call a method from another method in the same class with JavaScript.

In this article, we’ll look at how to call a method from another method in the same class with JavaScript.

How to call a method from another method in the same class with JavaScript?

To call a method from another method in the same class with JavaScript, we use this.

For instance, we write

class MyClass {
  myTest() {
    console.log("it works");
  }

  runMyTest() {
    this.myTest();
  }
}

const myClass = new MyClass();
myClass.runMyTest();

to call this.myTest in runMyTest to call the myTest method in runMyTest.

Conclusion

To call a method from another method in the same class with JavaScript, we use this.