Author: John Au-Yeung

Sometimes, we want to fetch an array of URLs with Promise.all with JavaScript.

In this article, we’ll look at how to fetch an array of URLs with Promise.all with JavaScript.

How to fetch an array of URLs with Promise.all with JavaScript?

To fetch an array of URLs with Promise.all with JavaScript, we call Promise.all with an array of promises.

For instance, we write

const texts = await Promise.all(
  urls.map(async (url) => {
    const resp = await fetch(url);
    return resp.text();
  })
);

to call urls.map with an async function that calls fetch and returns the response as the resolve value of the promise returned.

Then we call Promise.all with the array of promises returned by map to make the requests.

Next we get the responses from the texts array which we get from using await on the promise returned by Promise.all.

Conclusion

To fetch an array of URLs with Promise.all with JavaScript, we call Promise.all with an array of promises.

Sometimes, we want to remove line breaks from start and end of string with JavaScript.

In this article, we’ll look at how to remove line breaks from start and end of string with JavaScript.

How to remove line breaks from start and end of string with JavaScript?

To remove line breaks from start and end of string with JavaScript, we can use the string replace method.

For instance, we write

const newwStr = str.replace(/^\s+|\s+$/g, "");

to call replace to remove line breaks from the start and end of the string by replacing them with empty strings.

^\s+ matches the line break at the start of the string.

\s+$ matches the line break at the end of the string.

Conclusion

To remove line breaks from start and end of string with JavaScript, we can use the string replace method.

Sometimes, we want to run Node.js app with ES6 features enabled.

In this article, we’ll look at how to run Node.js app with ES6 features enabled.

How to run Node.js app with ES6 features enabled?

To run Node.js app with ES6 features enabled, we install a few packages.

We enable ES6 features by running

npm install --save-dev babel
npm install --save-dev babel-cli
npm install --save-dev babel-preset-es2015
npm install --save-dev babel-preset-stage-0
npm install --save-dev nodemon

to install Babel and nodemon.

Then we create a .babelrc file in the project root and add

{
  "presets": ["es2015", "stage-0"]
}

to let us run our project with ES6 features.

Then in package.json, we write

{
  //...
  "scripts": {
    "watch": "babel -w src/ -d dist/",
    "build": "babel src/ -d dist/",
    "serve": "babel -w src/ -d dist/ | nodemon --watch dist",
    "test": "echo \"Error: no test specified\" && exit 1"
  }
  //...
}

to run babel with nodemon to let us run our Node.js app with Babel.

Conclusion

To run Node.js app with ES6 features enabled, we install a few packages.