Javascript order of referencing

Question

What order does the following statement run? Does the runtime execute it from right to left?

  length = i = test = output = null;

Answer 1

Yes, since an assignment expression is not a lefthand-side expression itself, the nesting is

(length = (i = (test = (output = null))));

It is executed from outside-in, solving references left-to-right (first getting the length variable, then evaluating the right side, which is getting the i variable and evaluating …). That means output is the first variable that is getting assigned to, then test, then i, and last length: "right-to-left" if you want. Since the assignment operator always yields its right operand, everything will be assigned the same (innermost, rightmost) value: null.