Category: JavaScript Answers

Sometimes, we want to check that two objects have the same set of property names with JavaScript.

In this article, we’ll look at how to check that two objects have the same set of property names with JavaScript.

How to check that two objects have the same set of property names with JavaScript?

To check that two objects have the same set of property names with JavaScript, we use the Object.keys method.

For instance, we write

const compareKeys = (a, b) => {
  const aKeys = Object.keys(a).sort();
  const bKeys = Object.keys(b).sort();
  return JSON.stringify(aKeys) === JSON.stringify(bKeys);
};

to define the compareKeys function.

In it, we call Object.keys with a and b to get the keys from each object as arrays.

Then we call sort to return a sorted version of the arrays.

Next we compare the 2 key arrays after converting them to JSON strings with JSON.stringify.

Conclusion

To check that two objects have the same set of property names with JavaScript, we use the Object.keys method.

Sometimes, we want to press Enter button in Puppeteer and JavaScript.

In this article, we’ll look at how to press Enter button in Puppeteer and JavaScript.

How to press Enter button in Puppeteer and JavaScript?

To press Enter button in Puppeteer and JavaScript, we use the page.keyboard.press method.

For instance, we write

await page.keyboard.press("Enter");
await page.keyboard.press("NumpadEnter");

to call press with 'Enter' to press the enter key.

And we call press with 'NumpadEnter' to press the numpad enter key.

Conclusion

To press Enter button in Puppeteer and JavaScript, we use the page.keyboard.press method.

Sometimes, we want to implement binary search in JavaScript.

In this article, we’ll look at how to implement binary search in JavaScript.

How to implement binary search in JavaScript?

To implement binary search in JavaScript, we can search for the index of the item according to the comparison of the item at different indexes starting at the middle of the array.

For instance, we write

const binarySearch = (arr, val) => {
  let start = 0;
  let end = arr.length - 1;

  while (start <= end) {
    let mid = Math.floor((start + end) / 2);

    if (arr[mid] === val) {
      return mid;
    }

    if (val < arr[mid]) {
      end = mid - 1;
    } else {
      start = mid + 1;
    }
  }
  return -1;
};

to define the binarySearch function.

In it, we define the start and end variables set to the first and last indexes of the sorted arr array.

Then we use a while loop to search for the item as long as start is less than or equal to end.

We get the mid array index with Math.floor.

And we check if arr[mid] is val.

If it is, we return the mid index.

If val is less than arr[mid], then we set end to mid - 1 to narrow down the search.

Otherwise, we set start to mid + 1 to narrow down the search.

If nothing is found then -1 is returned.

Conclusion

To implement binary search in JavaScript, we can search for the index of the item according to the comparison of the item at different indexes starting at the middle of the array.

Sometimes, we want to compile an Electron application to an .exe with JavaScript.

In this article, we’ll look at how to compile an Electron application to an .exe with JavaScript.

How to compile an Electron application to an .exe with JavaScript?

To compile an Electron application to an .exe with JavaScript, we use Electron Packager.

To install it, we run

npm install electron-packager --save-dev

in our project folder.

We can also install it globally with

npm install electron-packager -g

Then we compile the project into an .exe with

electron-packager <sourcedir> <appname> --platform=win32 --arch=x86_64

Conclusion

To compile an Electron application to an .exe with JavaScript, we use Electron Packager.

Sometimes, we want to check if element exists using Cypress.io and JavaScript.

In this article, we’ll look at how to check if element exists using Cypress.io and JavaScript.

How to check if element exists using Cypress.io and JavaScript?

To check if element exists using Cypress.io and JavaScript, we use the find method.

For instance, we write

const $body = await cy.get("body");
if ($body.find("button[data-cy=appDrawerOpener]").length > 0) {
  //...
}

to call the get method to get the body element.

Then we check if a button with data-cy attribute set to appDrawerOpener in the body element with $body.find.

If it returns length bigger than 0, then it’s found.

Conclusion

To check if element exists using Cypress.io and JavaScript, we use the find method.