[Solved] How to write an inline IF statement in JavaScript?

How can I use an inline if statement in JavaScript? Is there an inline else statement too?

Something like this:

var a = 2;
var b = 3;

if(a < b) {
    // do something

Solution #1:

You don’t necessarily need jQuery. JavaScript alone will do this.

var a = 2;
var b = 3;    
var c = ((a < b) ? 'minor' : 'major');

The c variable will be minor if the value is true, and major if the value is false.

This is known as a Conditional (ternary) Operator.

Respondent: MattW

Solution #2:

There is a ternary operator, like this:

var c = (a < b) ? "a is less than b"  : "a is not less than b";
Respondent: Mahmoud Gamal

Solution #3:

For writing if statement inline, the code inside of it should only be one statement:

if ( a < b ) // code to be executed without curly braces;
Respondent: undefined

Solution #4:

You can also approximate an if/else using only Logical Operators.

(a && b) || c

The above is roughly the same as saying:

a ? b : c

And of course, roughly the same as:

if ( a ) { b } else { c }

I say roughly because there is one difference with this approach, in that you have to know that the value of b will evaluate as true, otherwise you will always get c. Bascially you have to realise that the part that would appear if () { here } is now part of the condition that you place if ( here ) { }.

The above is possible due to JavaScripts behaviour of passing / returning one of the original values that formed the logical expression, which one depends on the type of operator. Certain other languages, like PHP, carry on the actual result of the operation i.e. true or false, meaning the result is always true or false; e.g:

14 && 0          /// results as 0,  not false
14 || 0          /// results as 14, not true
1 && 2 && 3 && 4 /// results as 4,  not true
true && ''       /// results as ''
{} || '0'        /// results as {}

One main benefit, compared with a normal if statement, is that the first two methods can operate on the righthand-side of an argument i.e. as part of an assignment.

d = (a && b) || c;
d = a ? b : c;

if `a == true` then `d = b` else `d = c`

The only way to achieve this with a standard if statement would be to duplicate the assigment:

if ( a ) { d = b } else { d = c }

You may ask why use just Logical Operators instead of the Ternary Operator, for simple cases you probably wouldn’t, unless you wanted to make sure a and b were both true. You can also achieve more streamlined complex conditions with the Logical operators, which can get quite messy using nested ternary operations… then again if you want your code to be easily readable, neither are really that intuative.

Respondent: Pebbl

Solution #5:

In plain English, the syntax explained:


Can be written as:

condition ? do_something_if_condition_is_met : do_something_else_if_condition_is_not_met;
Respondent: Onimusha

Solution #6:

If you just want an inline IF (without the ELSE), you can use the logical AND operator:

(a < b) && /*your code*/;

If you need an ELSE also, use the ternary operation that the other people suggested.

Respondent: Nahn

Solution #7:

<div id="ABLAHALAHOO">8008</div>
<div id="WABOOLAWADO">1110</div>

parseInt( $( '#ABLAHALAHOO' ).text()) > parseInt( $( '#WABOOLAWADO ).text()) ? alert( 'Eat potato' ) : alert( 'You starve' );
Respondent: HyderA

Solution #8:

You could do like this in JavaScript:

a < b ? passed() : failed();
Respondent: Ivar

Solution #9:

FYI, you can compose conditional operators

var a = (truthy) ? 1 : (falsy) ? 2 : 3;

If your logic is sufficiently complex, then you might consider using an IIFE

var a = (function () {
  if (truthy) return 1;
  else if (falsy) return 2;
  return 3;

Of course, if you plan to use this logic more than once, then you aught to encapsulate it in a function to keep things nice and DRY.

Respondent: alan

Solution #10:

I often need to run more code per condition, by using: ( , , ) multiple code elements can execute:

var a = 2;
var b = 3;
var c = 0;

( a < b ?  ( alert('hi'), a=3, b=2, c=a*b ) : ( alert('by'), a=4, b=10, c=a/b ) );
Respondent: kurt

Solution #11:

To add to this you can also use inline if condition with && and || operators.
Like this

var a = 2;
var b = 0;

var c = (a > b || b == 0)? "do something" : "do something else";
Respondent: Anoop

Solution #12:

inline if:

(('hypothesis') ? 'truthy conclusion' : 'falsey conclusion')

truthy conclusion: statements executed when hypothesis is true

falsey conclusion: statements executed when hypothesis is false

your example:

var c = ((a < b) ? 'a<b statements' : '!(a<b) statements');
Respondent: Sammy

Solution #13:

Isn’t the question essentially: can I write the following?

if (foo)
  console.log(foo + bar)

the answer is, yes, the above will translate.

however, be wary of doing the following

if (foo)
  if (bar)

be sure to wrap ambiguous code in braces as the above will throw an exception (and similar permutations will produce undesired behaviour.)

Respondent: Jay Edwards

The answers/resolutions are collected from stackoverflow, are licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0 .

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