String constants cannot be modified, the reason for the array can be modified

In general, to get the string str= "Kuai Lai xiu gai wo" a character can be obtained by an array-like way, str[i], but can not be modified by str[i] = ' xx '. Unless the string is cut or converted to an array.

var str = "Beijing";
Str[0] = ' hahaha ';
Console.log (str);
Console.log (Str[0]);

None of the above results are B. At the moment, the result is that the string is created as a constant, stored in the heap, and cannot be modified. After the array is converted, the arrays are stored according to the stack, and the addresses can be accessed and modified.

For more detailed reasons, I think again, ask.