recently I have read tutorial from some of the web page about Javascript function that shuffles array. but some portion of the code I didn't understood completely. for ex:here is js fiddle
here i dont understand this code part
this[i] = this[j] + (this[j] = this[i],0);
what does it means (this[j] = this[i],0);
?
Thanks in advance
The code is just doing a 1-line swap.
You're familiar with the standard swap, correct?
A = 6, B = 10
X = A
A = B
B = X
now B = 6, and A = 10
Take a look at your tutorial code
this[i] = this[j] + (...) means that the assignment will not take place right away. Instead, the parenthetical must be calculated first. However, the browser will temporarily make a note of the value of this[j], essentially copying it to X.
(this[j] = this[i],0) can now be calculated, but what does the parenthesis return to be added to the outside this[j]? The 0! So inside the parenthesis, the second step of the swap took place, and 0 is added to the temporary X!
Now the calculation becomes this[i] = this[j] + 0. The third step of swap!
For any expression with commas, all expressions are executed and the last expression is returned.
var a = (1+1, 2+2, 3+3);
// a = 6
For the case above:
this[i] = this[j] + (this[j] = this[i], 0);
is equivalent to:
var temp = this[j];
this[j] = this[i];
this[i] = temp + 0;
The temp is automatically handled, because left-side (this[j]) is evaluated first.
(this[j] = this[i], 0) expression evaluates this[j] = this[i] and 0, and returns only the right-most expression (0). The 0 comes from there, and temp comes from this[j].