1303464 - every browser fails [1,2]==[1,2,3,4].slice(0,2)

Status: RESOLVED INVALID

(Firefox :: Untriaged, defect)

Description

[Jim Michaels]

User Agent: Mozilla/5.0 (Windows NT 6.0; rv:48.0) Gecko/20100101 Firefox/48.0
Build ID: 20160823121617

Steps to reproduce:

start ANY browser including IE9
start debugger (F12 or ctrl-shift-i)
into the console, put:
[1,2]==[1,2,3,4].slice(0,2)




Actual results:

false


Expected results:

true

Comment 1

[Tooru Fujisawa [:arai]]

you cannot compare the elements of arrays with == operator.
you need to compare each elements one by one.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Comparison_Operators#Equality
> If both operands are objects, then JavaScript compares internal references
> which are equal when operands refer to the same object in memory.

Comment 2

[Jim Michaels]

you can with c++ and other compiled languages, I don't understand any not js...

Comment 3

[Jim Michaels]

workaround:
function Array.prototype.equals(a) {
    for (var i=0; i < this.value.length; i++) {
         if ('object'==typeof(this.value)) {
             Array.prototype.equals(this.value[i],a[i]);
         } else {
             if (this.value[i]!=a[i]) {
                 return false;
             }
         }
    }
    return true;
}

Comment 4

[Jim Michaels]

that's not the finished version - but do you want to change this from resolved invalid to resolved-fixed (where is that select option anyway?)?