Category: JavaScript Answers

Sometimes, we want to change selected option by value in a HTML select element using JavaScript.

In this article, we’ll look at how to change selected option by value in a HTML select element using JavaScript.

How to change selected option by value in a HTML select element using JavaScript?

To change selected option by value in a HTML select element using JavaScript, we can set its value property.

For instance, we write

document.getElementById("sel").value = "bike";

to select the drop down with getElementById.

Then we set its value property to the value of the option element with the value we’re looking for.

Conclusion

To change selected option by value in a HTML select element using JavaScript, we can set its value property.

Sometimes, we want to remove color underneath lines from a Chart.js line charts with JavaScript.

In this article, we’ll look at how to remove color underneath lines from a Chart.js line charts with JavaScript.

How to remove color underneath lines from a Chart.js line charts with JavaScript?

To remove color underneath lines from a Chart.js line charts with JavaScript, we set the fill option to false.

For instance, we write

const data = {
  labels: ["January", "February", "March", "April", "May", "June", "July"],
  datasets: [
    {
      label: "Dataset",
      fill: false,
      data: [1, 2, 3],
    },
  ],
};

to set fill to false to remove the color underneath the lines in the line chart.

Conclusion

To remove color underneath lines from a Chart.js line charts with JavaScript, we set the fill option to false.

Sometimes, we want to convert object containing objects into array of objects with JavaScript.

In this article, we’ll look at how to convert object containing objects into array of objects with JavaScript.

How to convert object containing objects into array of objects with JavaScript?

To convert object containing objects into array of objects with JavaScript, we can use the Object.values method.

For instance, we write

const data = {
  a: { 0: "1" },
  b: { 1: "2" },
  c: { 2: "3" },
  d: { 3: "4" },
};

const newArrayDataOfOjbect = Object.values(data);

to call Object.values with data to return an array of property values from the data object.

Conclusion

To convert object containing objects into array of objects with JavaScript, we can use the Object.values method.

Sometimes, we want to convert CSV to JSON in Node.js and JavaScript.

In this article, we’ll look at how to convert CSV to JSON in Node.js and JavaScript.

How to convert CSV to JSON in Node.js and JavaScript?

To convert CSV to JSON in Node.js and JavaScript, we use the csvtojson library.

To install it, we run

npm i csvtojson

Then we use it by writing

const csv = require("csvtojson");

const csvFilePath = "customer-data.csv";
const jsonObj = await csv().fromFile(csvFilePath);
console.log(jsonObj);

to call fromFile with the csvFilePath to read the csv file and return a promise with the csv data parsed into a JavaScript object.

And then we use await to get the data from the returned promise.

Conclusion

To convert CSV to JSON in Node.js and JavaScript, we use the csvtojson library.

Sometimes, we want to call an asynchronous function within map with JavaScript.

In this article, we’ll look at how to call an asynchronous function within map with JavaScript.

How to call an asynchronous function within map with JavaScript?

To call an asynchronous function within map with JavaScript, we can use the Promise.all method.

For instance, we write

const data = await Promise.all(
  data.map(async (item) => {
    try {
      item.fetchItem = await fetchFunc(item.fetchParams);

      return item;
    } catch (err) {
      throw err;
    }
  })
);

to call data.map with an async function as its callback.

The callback’s return statement returns the resolve value of the promise returned by the async function.

Then we call Promise.all on the returned array of promises to return a promise with an array of resolve value of each async function.

And then we use await to get the array of resolve values.

Conclusion

To call an asynchronous function within map with JavaScript, we can use the Promise.all method.