function a() {
var b = ["b"];
console.log(b);
//console.log(b.slice());
b = b.push("bb");
}
a();
In a "perfect" world you would think that the console.log would show ["b"] , but wildly enough it shows ["b", "bb"] even though "bb" isn't pushed on until afterword . *wtf*
If you do console.log(b.slice()); Then you will get the desired result of ["b"] . What gives? What's the reason behind this complication? I just want to understand this better so I can better avoid it from happening.
*note I hit on this same point in a recent question of mine, but this is a much more concise example. @RightSaidFred has led me to this point and has been a HUGE help so far (big thanks).
** EDIT **
** POST-ANSWER **
This is all due to a problem where console.log messes up sometimes. Thanks to everyone for all the help in figuring this out.
Source: Tips4all
This is a known problem with console.log.
ReplyDeleteInstead of turning the parameter into a string when you call the method, the parameter is stored and turned into a string when it's displayed in the UI. As nothing happens in the UI while the function is running, you will see the state of the object as it is when you exit the function.
I'm assuming this has to do with the way that console.log() works although you're doing something a little funky when you say:
ReplyDeleteb = b.push("bb");
you should be able to just say
b.push("bb");
Confirmation (if needed) of Guffa's answer :
ReplyDeletefunction a() {
var b = ["b"];
console.log (b);
console.log (' ' + b);
console.log (b);
console.log (b.toString ());
console.log (b);
b = b.push("bb");
console.log (b);
}
a();
Chrome outputs :
["b", "bb"]
b
["b", "bb"]
b
["b", "bb"]
2
Note how every log referencing the object shows the "anomolous" result and each one which requires the evaluation of an expression does not. Note also the final log which shows that b is set to the value value 2, since the value returned by push is the new length of the array.
So, to avoid this issue ensure that each log parameter involves the evaluation of an expression.
I think it's a bug on the google chrome dev tools
ReplyDelete