Category: JavaScript Answers

Sometimes, we want to change onclick action with a JavaScript function.

In this article, we’ll look at how to change onclick action with a JavaScript function.

How to change onclick action with a JavaScript function?

To change onclick action with a JavaScript function, we can set the element’s onclick property to a function that runs when we click on the element.

For instance, we write

document.getElementById(`${id}-button`).onclick = () => {
  hideError(id);
};

to select the element with getElementById.

Then we set its onclick property to a function that calls the hideError function.

Conclusion

To change onclick action with a JavaScript function, we can set the element’s onclick property to a function that runs when we click on the element.

Sometimes, we want to get JavaScript select box’s selected text.

In this article, we’ll look at how to get JavaScript select box’s selected text.

How to get JavaScript select box’s selected text?

To get JavaScript select box’s selected text, we can use the select element’s options and selectedIndex properties.

For instance, we write

const sel = document.getElementById("selectBox");
const text = sel.options[sel.selectedIndex].text;

to select the select element with getElementById.

Then we get the index of the selected option with sel.selectedIndex.

Next we use that with sel.options to get the option that’s selected.

And then get the text of the option with the text property.

Conclusion

To get JavaScript select box’s selected text, we can use the select element’s options and selectedIndex properties.

Sometimes, we want to write formatted JSON in Node.js.

In this article, we’ll look at how to write formatted JSON in Node.js.

How to write formatted JSON in Node.js?

To write formatted JSON in Node.js, we can use the JSON.stringify method.

For instance, we write

const output = JSON.parse(json);
const printToFile = JSON.stringify(output, null, "\t");

to call JSON.parse to parse the json JSON string into an object.

Then we call JSON.stringigfy with output and '\t' to return a JSON string that has indentation with tabs.

Conclusion

To write formatted JSON in Node.js, we can use the JSON.stringify method.

Sometimes, we want to calculate page load time in JavaScript.

In this article, we’ll look at how to calculate page load time in JavaScript.

How to calculate page load time in JavaScript?

To calculate page load time in JavaScript, we can use properties in the window.performance.timing property.

For instance, we write

const loadTime =
  window.performance.timing.domContentLoadedEventEnd -
  window.performance.timing.navigationStart;

window.performance.timing.domContentLoadedEventEnd is the timestamp when DOM finished loading.

And window.performance.timing.navigationStart is the timestamp when navigation started.

We subtract window.performance.timing.domContentLoadedEventEnd by window.performance.timing.navigationStart to get the page load time in milliseconds.

Conclusion

To calculate page load time in JavaScript, we can use properties in the window.performance.timing property.

Sometimes, we want to fix the Expected ‘this’ to be used by class method error with JavaScript.

In this article, we’ll look at how to fix the Expected ‘this’ to be used by class method error with JavaScript.

How to fix the Expected ‘this’ to be used by class method error with JavaScript?

To fix the Expected ‘this’ to be used by class method error with JavaScript, we should change the function causing the error to an arrow function.

For instance, we write

const getUrlParams = (queryString) => {
  //...
};

to define the getUrlParams as an arrow function.

Then if it doesn’t reference this, then the error would go away.

Conclusion

To fix the Expected ‘this’ to be used by class method error with JavaScript, we should change the function causing the error to an arrow function.