2 Useful Tips about JavaScript Conditionals

Lear more about JavaScript If condition through this small JavaScript article. Read this short JavaScript tutorial, practice yourself with some tiny JavaScript If examples to understand and use JavaScript if clause smarter and better.


Sampled by © JavaScriptBank.com

Just a quick post, inspired by Laura Kalbag's post, which included this gem:

We shouldn't be fearful of writing about what we know. Even if you write from the most basic point of view, about something which has been 'around for ages', you'll likely be saying something new to someone.

One: There is no else if

When you write something like this ...

function saySomething( msg ) {
  if ( msg === 'Hello' ) {
    console.log('Hello there');
  } else if ( msg === 'Yo' ) {
    console.log('Yo dawg');
  }
}

... then what you're actually writing is this ...

function saySomething( msg ) {
  if ( msg === 'Hello' ) {
    console.log('Hello there');
  } else {
    if ( msg === 'Yo' ) {
      console.log('Yo dawg');
    }
  }
}

That's because there is no else if in JavaScript. You know how you can write an if statement without any curly braces?

if ( foo ) bar() // please don't do this if you want your code to be legible

You're doing the same thing with the else part of the initial if statement when you write else if: you're skipping the curly braces for the second if block, the one you're providing to else. There's nothing wrong with else if per se, but it's worth knowing about what's actually happening.

Two: return Means Never Having to Say else

Consider some code like this:

function howBig( num ) {
  if ( num < 10 ) {
    return 'small';
  } else if ( num >= 10 && num < 100 ) {
    return 'medium';
  } else if ( num >= 100 ) {
    return 'big';
  }
}

If the number we pass to howBig is less than 10, then our function will return 'small'. As soon as it returns, none of the rest of the function will run – this means we can skip the else part entirely, which means our JavaScript code could look like this:

function howBig( num ) {
  if ( num < 10 ) {
    return 'small';
  }

  if ( num < 100 ) {
    return 'medium';
  }

  if ( num >= 100 ) {
    return 'big';
  }
}

But wait – if the first if statement isn't true, and the second if statement isn't true, then we will always return 'big'. That means the third if statement isn't even required:

function howBig( num ) {
  if ( num < 10 ) {
    return 'small';
  }

  if ( num < 100 ) {
    return 'medium';
  }

  return 'big';
}

From

Link: http://rmurphey.com/blog/2012/12/10/js-conditionals

Language
Translate this page to English Translate this page to French Translate this page to Vietnamese

Recent articles
Insights for Advanced Zooming and Panning in JavaScript Charts
How to open a car sharing service
Vue developer as a vital part of every software team
Vue.js developers: hire them, use them and get ahead of the competition
3 Reasons Why Java is so Popular
Migrate to Angular: why and how you should do it
The Possible Working Methods of Python Ideology
JavaScript Research Paper: 6 Writing Tips to Craft a Masterpiece
Learning How to Make Use of New Marketing Trends
5 Important Elements of an E-commerce Website


Top view articles
Adding JavaScript to WordPress Effectively with JavaScript Localization feature
Top 10 Beautiful Christmas Countdown Timers
Top 10 Best JavaScript eBooks that Beginners should Learn
65 Free JavaScript Photo Gallery Solutions
16 Free Code Syntax Highlighters by Javascript For Better Programming
Best Free Linux Web Programming Editors
Top 50 Most Addictive and Popular Facebook mini games
More 30 Excellent JavaScript/AJAX based Photo Galleries to Boost your Sites
Top 10 Free Web Chat box Plug-ins and Add-ons
The Ultimate JavaScript Tutorial in Web Design


Free JavaScript Tutorials & Articles
at www.JavaScriptBank.com