What does this mean? Is it an if else representation?

Question

What does the following mean?

    var iCurrentIndex = oCurrentQuestionModel.getProperty("/index"); ...(1)
    iCurrentIndex = iCurrentIndex ? ++iCurrentIndex : 0; ...(2)

The var iCurrentIndex = false in setp 1 and in step 2 it gets assigned value 0. What does this representation mean can anyone explain me?

It's a ternary: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator — Jeremy Jackson, May 12 '17 at 12:18

score 0 · Answer 1 · answered May 12 '17 at 12:18

0

Your step 2 can be rewritten like this:

if (iCurrentIndex) {
    ++iCurrentIndex;
} else {
    return 0;
}

You are using ternary operator, read about it here.

answered May 12 '17 at 12:18

errata

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Thank you the link was useful but why would someone use a ternary operator instead of if and else? just curious – loki May 12 '17 at 12:24
If you have a short conditional sometimes it's ok to put it on one line instead of 5 :) – Jeremy Jackson May 12 '17 at 12:25
@loki It's just a matter of personal preference, readability or shorter code... – errata May 12 '17 at 12:28

Nina Scholz · Answer 2 · 2017-05-12T12:26:07.190

0

Assuming

var iCurrentIndex = oCurrentQuestionModel.getProperty("/index");

returns an undefined or null or just false, then an increment can not take place.

Then you need a check if the returned value is truthy (a value which resolves to true, if casted to boolean), then just increment or assign zero to iCurrentIndex.

iCurrentIndex = iCurrentIndex ? ++iCurrentIndex : 0;

The above conditional oparator uses a condition and evaluates either the part after ?, the then part of an if statement or the part after :, the else part of an if statement.

edited May 12 '17 at 12:26

answered May 12 '17 at 12:21

Nina Scholz

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Thank you. So is ternary operator preferred more over if else statements? – loki May 12 '17 at 12:25
@loki, actually, you make an increment **and** an assignment so it is not really a good example of using a conditional operator. – Nina Scholz May 12 '17 at 12:28

What does this mean? Is it an if else representation?

2 Answers2