What would be the explanation for the strange javascript expression? -


in javascript following line of code gives answer 1

+ ! {} [true]

i couldn't understand how?

any gurus explanation appreciated.

{} empty object.

so {}[0] or {}[true] or {}[1] etc.. undefined

adding ! casts {}[0] boolean, returning opposite. (undefined becoming false, therefore returns true).

adding + casts int, true becomes 1.


Comments

Post a Comment

Popular posts from this blog

matlab - How to equate a structure array to structure array -

the following code doesn't work, think it's clear want do: my.struct = 1; foo.bar = my.struct; so that foo.bar.struct = 1 basically want fill in my structure array bunch of fields , values. want place struct nested struct within foo.bar while retaining field names. my.struct = 1; foo.bar = my.struct; this places value of my.struct (= 1 ) in foo.bar . of course foo.bar 1 . i think you're after this: my.struct = 1 foo.bar = my;
Read more

c# - Operator '==' incompatible with operand types 'Guid' and 'Guid' using DynamicExpression.ParseLambda<T, bool> -

i'm using dynamic linq library , there source code , basic docu , nuget version pm> install-package dynamiclinq i'm trying construct clause involves guids i have tried string "id == @0" . parameter array object[] value ( guid xxxx ) var whereclausesb = buildlogicalkeywhereclause2(entity, logicalkey); //build string var parms = buildparamarray(entity, logicalkey); // object[] var wherelambda = ofsi.bos.core.dynamicexpression.parselambda<t, bool>(whereclausesb.tostring(),parms); //parse an exception thrown in dynamicexpression.parselambda operator '==' incompatible operand types 'guid' , 'guid' i have tried guid , string.(fail) i tried , "id = @0" (fail). string == string works, int32==int32 not guid == guid not any ideas? try using equals method instead of == operator in string: "id.equals(@0)"
Read more