What does the '&&' expression mean in this snippet of JavaScript?

Question

Hi, I recently got a piece of JavaScript code snippet from here.

Could someone please explain how this statement works: (jq=jq.slice(1)).length && hidenext(jq);in the function below?

(function hidenext(jq){
    jq.eq(0).fadeOut("fast", function(){
        (jq=jq.slice(1)).length && hidenext(jq);
    });
})($('div#bodyContent a'))

The answer is here : https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/Logical_Operators — Denys Séguret, Mar 25 '13 at 17:56
possible duplicate of [&& operator in Javascript](http://stackoverflow.com/questions/8720645/operator-in-javascript) — epascarello, Mar 25 '13 at 17:59

score 7 · Accepted Answer · answered Mar 25 '13 at 17:57

7

Here, as the result isn't used, the logical AND is used as a kind of short if.

It's the same as

if ((jq=jq.slice(1)).length) hidenext(jq);

It uses the fact that the second part won't be evaluated if the first one doesn't evaluate as true.

answered Mar 25 '13 at 17:57

Denys Séguret

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Christopher Swasey · Answer 2 · 2013-03-25T18:06:39.960

2

It means that hidenext(jq) will only be called if jq (now set to the return value of jq.slice(1) has a length > 0. Because && is short-circuited, evaluation is halted if the first operand is falsy.

edited Mar 25 '13 at 18:06

answered Mar 25 '13 at 17:58

Christopher Swasey

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What does the '&&' expression mean in this snippet of JavaScript?

2 Answers2

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