Author: John Au-Yeung

Web developer specializing in React, Vue, and front end development.

Categories
Vue Answers

How to listen to the window scroll event in a Vue.js component?

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Sometimes, we want to listen to the window scroll event in a Vue.js component.

In this article, we’ll look at how to listen to the window scroll event in a Vue.js component.

How to listen to the window scroll event in a Vue.js component?

To listen to the window scroll event in a Vue.js component, we can call window.addEventListener.

For instance, we write

export default {
  created() {
    window.addEventListener("scroll", this.handleScroll);
  },
  destroyed() {
    window.removeEventListener("scroll", this.handleScroll);
  },
  methods: {
    handleScroll(event) {
      // ...
    },
  },
};

to call window.addEventListener in the created hook to add the handleScroll method as the callback for the scroll event when the component is loading.

In the destroyed hook, we call window.removeEventListener to remove handleScroll as the scroll event listener when the component unmounts.

Conclusion

To listen to the window scroll event in a Vue.js component, we can call window.addEventListener.

Categories
JavaScript Answers

How to remove all multiple spaces in JavaScript and replace with single space?

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Sometimes, we want to remove all multiple spaces in JavaScript and replace with single space.

In this article, we’ll look at how to remove all multiple spaces in JavaScript and replace with single space.

How to remove all multiple spaces in JavaScript and replace with single space?

To remove all multiple spaces in JavaScript and replace with single space, we use the string replace method with a regex.

For instance, we write

str = str.replace(/ +(?= )/g, "");

to call str.replace with the / +(?= )/g regex to match all instances of multiple spaces in the str string.

We use +(?= ) to match multiple spaces.

And we use the g flag to find all matches.

Then we replace them all with empty strings.

Conclusion

To remove all multiple spaces in JavaScript and replace with single space, we use the string replace method with a regex.

Categories
JavaScript Answers

How to find the longest string in an array with JavaScript?

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Sometimes, we want to find the longest string in an array with JavaScript.

In this article, we’ll look at how to find the longest string in an array with JavaScript.

How to find the longest string in an array with JavaScript?

To find the longest string in an array with JavaScript, we can use the array map and Math.max methods.

For instance, we write

const longest = Math.max(...arr.map((el) => el.length));
'``

to call `arr.map` with a callback that returns the `length` of each string `el` and return the lengths in an array.

Then we call `Math.max` with the array entries spread into it as arguments.

This will then return the length of the longest string in `arr`.

### Conclusion

To find the longest string in an array with JavaScript, we can use the array `map` and `Math.max` methods.
Categories
JavaScript Answers

How to copy and paste from Excel to a web page with JavaScript?

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Sometimes, we want to copy and paste from Excel to a web page with JavaScript.

In this article, we’ll look at how to copy and paste from Excel to a web page with JavaScript.

How to copy and paste from Excel to a web page with JavaScript?

To copy and paste from Excel to a web page with JavaScript, we can paste the data into the page as HTML.

For instance, we write

document.onpaste = (event) => {
  const data = event.clipboardData.getData("text/html");
  //...
};

to set the document.onpaste property to a function that’s called when we paste in some data onto the page.

In the function, we get the pasted data as HTML with

event.clipboardData.getData("text/html")

Then we can do whatever with it after that after assign it to data.

Conclusion

To copy and paste from Excel to a web page with JavaScript, we can paste the data into the page as HTML.

Categories
JavaScript Answers

How to name a JavaScript function and execute it immediately?

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Sometimes, we want to name a JavaScript function and execute it immediately.

In this article, we’ll look at how to name a JavaScript function and execute it immediately.

How to name a JavaScript function and execute it immediately?

To name a JavaScript function and execute it immediately, we can use an IIFE.

For instance, we write

(function addEventsAndStuff() {
  //...
})();

to define the addEventsAndStuff function and then call it immediately by wrapping it in parentheses.

And then we call it with ().

Conclusion

To name a JavaScript function and execute it immediately, we can use an IIFE.