19+ JavaScript Shorthand Coding Techniques

improve-your-javascript

This really is a must read for any JavaScript based developer. I have made this post as a vital source of reference for learning shorthand JavaScript coding techniques that I have picked up over the years. To help you understand what it going on I have included the longhand versions to give some coding perspective on the shorts.

Update 05/05/2013 – There are now 19 strong keep em coming! :)

  • Step 1 – Learn the JavaScript shorthand techniques.
  • Step 2 – Save valuable coding time by keeping your code to a minimum.
  • Step 3 – Impress your colleagues with your awesome new coding skillz!

It’s as easy as steps 1,2,3. Here they are.

1. If true … else Shorthand

This is a great code saver for when you want to do something if the test is true, else do something else by using the ternary operator.

Longhand:

var big;
if (x > 10) {
    big = true;
}
else {
    big = false;
}

Shorthand:

var big = (x > 10) ? true : false;

If you rely on some of the weak typing characteristics of JavaScript, this can also achieve more concise code. For example, you could reduce the preceding code fragment to this:

var big = (x > 10);

//further nested examples
var x = 3,
big = (x > 10) ? "greater 10" : (x < 5) ? "less 5" : "between 5 and 10";
console.log(big); //"less 5"

var x = 20,
big = {true: x>10, false : x<=10};
console.log(big); //"Object {true=true, false=false}"

2. Null, Undefined, Empty Checks Shorthand

When creating new variables sometimes you want to check if the variable your referencing for it’s value isn’t null or undefined. I would say this is a very common check for JavaScript coders.

Longhand:

if (variable1 !== null || variable1 !== undefined || variable1 !== '') {
     var variable2 = variable1;
}

Shorthand:

var variable2 = variable1  || '';

Don’t believe me? Test it yourself (paste into Firebug and click run):

//null value example
var variable1 = null;
var variable2 = variable1  || '';
console.log(variable2);
//output: '' (an empty string)

//undefined value example
var variable1 = undefined;
var variable2 = variable1  || '';
console.log(variable2);
//output: '' (an empty string)

//normal value example
var variable1 = 'hi there';
var variable2 = variable1  || '';
console.log(variable2);
//output: 'hi there'

3. Object Array Notation Shorthand

Useful way of declaring small arrays on one line.

Longhand:

var a = new Array();
a[0] = "myString1";
a[1] = "myString2";
a[2] = "myString3";

Shorthand:

var a = ["myString1", "myString2", "myString3"];

4. Associative Array Notation Shorthand

The old school way of setting up an array was to create a named array and then add each named element one by one. A quicker and more readable way is to add the elements at the same time using the object literal notation. Please note that Associative Array are essentially JavaScript Objects with properties.

Longhand:

var skillSet = new Array();
skillSet['Document language'] = 'HTML5';
skillSet['Styling language'] = 'CSS3';
skillSet['Javascript library'] = 'jQuery';
skillSet['Other'] = 'Usability and accessibility';

Shorthand:

var skillSet = {
    'Document language' : 'HTML5',
    'Styling language' : 'CSS3',
    'Javascript library' : 'jQuery',
    'Other' : 'Usability and accessibility'
};

Don’t forget to omit the final comma otherwise certain browsers will complain (not naming any names, IE).

5. Declaring variables Shorthand

It is sometimes good practice to including variable assignments at the beginning of your functions. This shorthand method can save you lots of time and space when declaring multiple variables at the same time.

longhand:

var x;
var y;
var z = 3;

shorthand:

var x, y, z=3;

6. Assignment Operators Shorthand

Assignment operators are used to assign values to JavaScript variables and no doubt you use arithmetic everyday without thinking (no matter what programming language you use Java, PHP, C++ it’s essentially the same principle).

Longhand:

x=x+1;
minusCount = minusCount - 1;
y=y*10;

Shorthand:

x++;
minusCount --;
y*=10;

Other shorthand operators, given that x=10 and y=5, the table below explains the assignment operators:

x += y //result x=15
x -= y //result x=5
x *= y //result x=50
x /= y //result x=2
x %= y //result x=0

7. RegExp Object Shorthand

Example to avoid using the RegExp object.

Longhand:

var re = new RegExp("\\d+(.)+\\d+","igm"),
result = re.exec("padding 01234 text text 56789 padding");
console.log(result); //"01234 text text 56789"

Shorthand:

var result = /\d+(.)+\d+/igm.exec("padding 01234 text text 56789 padding");
console.log(result); //"01234 text text 56789"

8. If Presence Shorthand

This might be trivial, but worth a mention. When doing “if checks” assignment operators can sometimes be ommited.

Longhand:

if (likeJavaScript == true)

Shorthand:

if (likeJavaScript)

Here is another example. If “a” is NOT equal to true, then do something.

Longhand:

var a;
if ( a != true ) {
// do something...
}

Shorthand:

var a;
if ( !a ) {
// do something...
}

9. Function Variable Arguments Shorthand

Object literal shorthand can take a little getting used to, but seasoned developers usually prefer it over a series of nested functions and variables. You can argue which technique is shorter, but I enjoy using object literal notation as a clean substitute to functions as constructors.

Longhand:

function myFunction( myString, myNumber, myObject, myArray, myBoolean ) {
    // do something...
}
myFunction( "String", 1, [], {}, true );

Shorthand (looks long but only because I have console.log’s in there!):

function myFunction() {
    console.log( arguments.length ); // Returns 5
    for ( i = 0; i < arguments.length; i++ ) {
        console.log( typeof arguments[i] ); // Returns string, number, object, object, boolean
    }
}
myFunction( "String", 1, [], {}, true );

10. JavaScript foreach Loop Shorthand

This little tip is really useful if you want plain JavaScript and hence can’t use jQuery.each or Array.forEach().

Longhand:

for (var i = 0; i < allImgs.length; i++)

Shorthand:

for(var i in allImgs)

Shorthand for Array.forEach:

function logArrayElements(element, index, array) {
    console.log("a[" + index + "] = " + element);
}
[2, 5, 9].forEach(logArrayElements);
// logs:
// a[0] = 2
// a[1] = 5
// a[2] = 9

11. charAt() Shorthand

You can use the eval() function to do this but this bracket notation shorthand technique is much cleaner than an evaluation, and you will win the praise of colleagues who once scoffed at your amateur coding abilities!

Longhand:

"myString".charAt(0);

Shorthand:

"myString"[0]; // Returns 'm'

12. Comparison returns

We’re no longer relying on the less reliable == as !(ret == undefined) could be rewritten as !(ret) to take advantage of the fact that in an or expression, ret (if undefined or false) will skip to the next condition and use it instead. This allows us to trim down our 5 lines of code into fewer characters and it’s once again, a lot more readable.

Longhand:

    if (!(ret == undefined)) {
        return ret;
    } else{
       return fum('g2g');
    }

Shorthand:

return ret || fum('g2g');

13. Short function calling

Just like #1 you can use ternary operators to make function calling shorthand based on a conditional.

Longhand:

function x() {console.log('x')};function y() {console.log('y')};
var z = 3;
if (z == 3)
{
    x();
} else
{
    y();
}

Shorthand:

function x() {console.log('x')};function y() {console.log('y')};var z = 3;
(z==3?x:y)(); // Short version!

14. Switch Knightmare

Everyone loves switch statements, *cough*. Here is how you might avoid switch case syndrome.

Longhand:

switch (something) {
 
    case 1:
        doX();
    break;
 
    case 2:
        doY();
    break;
 
    case 3:
        doN();
    break;
 
    // And so on...
 
}

Shorthand:

var cases = {
    1: doX,
    2: doY,
    3: doN
};
if (cases[something]) {
    cases[something]();
}

15. Decimal base exponents

You may have seen this one around it’s essentially a fancy way to write without the zeros. 1e7 essentially means 1 followed by 7 zeros – it represents a decimal base (JS interprets as a float type) equal to 10,000,000.

Longhand:

for (var i = 0; i < 10000; i++) {

Shorthand:

for (var i = 0; i < 1e7; i++) {

16. Decimal base exponents

You can use 1 and 0 to represent true and false. I’ve seen this used in JavaScript game development in shorthand while loops. Note that if you use the negative start your array may be in reverse. You can also use while(i++<10) and you don't have to add the i++ later on inside the while.

Longhand:

var i=0;
while (i<9)
{
  //do stuff
  i++; //say
}

Shorthand:

var i=9;
while(i--)
{
    //goes until i=0
}

or

var i=-9;
while(i++)
{
    //goes until i=0
}

17. Shorter IF’z

If you have mutiple IF variable value comparisons you can simply ass them to an array and check for presence. You could use $.inArray as an alternative.

Longhand:

if( myvar==1 || myvar==5 || myvar==7 || myvar==22 ) alert('yeah')

Shorthand:

if([1,5,7,22].indexOf(myvar)!=-1) alert('yeah baby!')

18. Lookup Tables Shorthand

If you have code that behaves differently based on the value of a property, it can often result in conditional statements with multiple else ifs or a switch cases. You may prefer to use a lookup table if there is more than two options (even a switch statement looks ugly!).

Longhand:

if (type === 'aligator')
{
    aligatorBehavior();
}
else if (type === 'parrot')
{
    parrotBehavior();
}
else if (type === 'dolphin')
{
    dolphinBehavior();
}
else if (type === 'bulldog')
{
    bulldogBehavior();
}
else
{
    throw new Error('Invalid animal ' + type);
}

Shorthand:

var types = {
  aligator: aligatorBehavior,
  parrot: parrotBehavior,
  dolphin: dolphinBehavior,
  bulldog: bulldogBehavior
};

var func = types[type];
if (!func) throw new Error('Invalid animal ' + type); func();

19. Double Bitwise

The double bitwise trick provides us with some pretty nifty shorthand tricks. Read more about it here: Double bitwise NOT (~~).

Longhand:

Math.floor(4.9) === 4  //true

Shorthand:

~~4.9 === 4  //true

20. Suggest one?

I really do love these and would love to find more, please leave a comment!