javascript - Comparison to -1 or undefined don t work, either with == or === -

here sample of code:

do {     line=gets(smil);     if (line===-1){console.log("abort");callback(-1);}     console.log("line= "+line); }while(line.search("<video")===-1); 

the first output goes well, suddenly, get

line= -1 typeerror: object -1 has no method 'search' 

gets custom function, wich return either string or -1 in case of error.

i tried == instead of ===, same.

i tried replace return -1 of gets undefined, get

line= undefined typeerror: cannot call method 'search' of undefined 

instead.

why if don t execute?

edit: tried with

var pline {     pline=gets(smil);     if (pline===-1){console.log("abort");callback(-1);}     console.log("line= "+pline); }while(pline.search("<video")===-1); 

to avoid overriding variable, got same result

it's two-fer question.

1st - you're overwriting variable line right after do. that's why you're getting uncaught typeerror: object -1 has no method 'search'

change line parsed_line = gets(smil); //also never forget semicolons

2nd - search isn't function of string, want indexof() function.

so change while(line.search()) while(line.indexof()).

i made fiddle demonstrates here