Category: JavaScript Answers

Sometimes, we want to add JavaScript callback that runs when an iframe is finished loading.

In this article, we’ll look at how to add JavaScript callback that runs when an iframe is finished loading.

How to add JavaScript callback that runs when an iframe is finished loading?

To add JavaScript callback that runs when an iframe is finished loading, we can listen for the readystatechange event.

To do this, we write

const iframe = document.getElementById("myIframe");

iframe.onreadystatechange = () => {
  if (iframe.readyState === "complete") {
    // ...
  }
};

to select the iframe with getElementById.

Then we set iframe.onreadystatechange to a function that runs when the readyState property changes.

If readyState for the iframe is 'complete', then the iframe‘s content is done loading.

Conclusion

To add JavaScript callback that runs when an iframe is finished loading, we can listen for the readystatechange event.

Sometimes, we want to do fuzzy search with JavaScript.

In this article, we’ll look at how to do fuzzy search with JavaScript.

How to do fuzzy search with JavaScript?

To do fuzzy search with JavaScript, we use the fuzzaldrin library.

To install it, we run

npm install fuzzaldrin

Then we use it by writing

const fuzzaldrin = require("fuzzaldrin");
const matches = fuzzaldrin.filter(["international", "splint", "tinder"], "int");

to call fuzzaldrin.filter with an array of possible matches and the search string we’re searching with.

Then filter returns an array of fuzzy search matches for searching for matches for 'int' in ["international", "splint", "tinder"].

Conclusion

To do fuzzy search with JavaScript, we use the fuzzaldrin library.

Sometimes, we want to detect text area onchange event with JavaScript.

In this article, we’ll look at how to detect text area onchange event with JavaScript.

How to detect text area onchange event with JavaScript?

To detect text area onchange event with JavaScript, we listen for the input event.

For instance, we write

const area = container.querySelector("textarea");
area.addEventListener(
  "input",
  () => {
    // ...
  },
  false
);

to select the textarea element with querySelector.

Then we call addEventListener on the element with 'input' and a callback that runs when we change the textarea input value.

We call addEventListener to listen for the input event on the textarea.

Conclusion

To detect text area onchange event with JavaScript, we listen for the input event.

Sometimes, we want to iterate over object keys in Node.js and JavaScript

In this article, we’ll look at how to iterate over object keys in Node.js and JavaScript.

How to iterate over object keys in Node.js and JavaScript?

To iterate over object keys in Node.js and JavaScript, we use the Object.keys method to get the object’s non-inherited keys in an array.

For instance, we write

Object.keys(obj).forEach((key) => {
  //...
});

to call Object.keys with obj to return an array of non-inherited object string keys.

Then we call forEach with a callback that gets the key from the callback parameter.

Conclusion

To iterate over object keys in Node.js and JavaScript, we use the Object.keys method to get the object’s non-inherited keys in an array.

Sometimes, we want to get the arguments called in a Jest mock function with JavaScript.

In this article, we’ll look at how to get the arguments called in a Jest mock function with JavaScript.

How to get the arguments called in a Jest mock function with JavaScript?

To get the arguments called in a Jest mock function with JavaScript, we call toHaveBeenCalledWith.

For instance, we write

expect(mockedFunction).toHaveBeenCalledWith("param1", "param2");

to call expect with the function we mocked.

And then we call toHaveBeenCalledwith with the arguments that we want to check the mockedFunction is called with.

This is done in our test callback.

Conclusion

To get the arguments called in a Jest mock function with JavaScript, we call toHaveBeenCalledWith.