How can '+myVar;' be a valid syntax

Question

I just got a bug that took some of my time to spot my searching filters weren't working because of the following code :

queryObject.search='valid==true';+searchQuery;

The good syntax is to mive the ';' in the string :

queryObject.search='valid==true;'+searchQuery;

The reasn why i didn't spot that is because the earlier line of code didn't triggered any javascript console error. So it seems it's a valid syntax.

So here is my question, how can this be a valid syntax ?

It's implicit numeric conversion. `-variable` is an implicit `variable *= -1` — VLAZ, Sep 27 '16 at 07:32
strange i did search for '+myVar' on google but i didn't get that. Sorry for the dup — Walfrat, Sep 27 '16 at 07:33
@Walfrat Searchs on operators in programming are always hard until you just look at the list of operators in a good documentation (the MDN is the best one for JS). — Denys Séguret, Sep 27 '16 at 07:34
In fairness, google isn't really good on searching programm-y things like `+word` as it will search for `word`. — VLAZ, Sep 27 '16 at 07:34

score 3 · Accepted Answer · answered Sep 27 '16 at 07:32

3

+something is an expression using the plus unary operator.

Its general purpose is to convert a value, for example a string, to a number.

answered Sep 27 '16 at 07:32

Denys Séguret

score 1 · Answer 2 · edited May 23 '17 at 12:24

1

+ is unary operator, which tries to get numeric value from variable.

There is a thread about it.

edited May 23 '17 at 12:24

Community

answered Sep 27 '16 at 07:32

Jakub Jankowski

2 Answers2