Usage of comma operators should be avoided JS-0090
Anti-pattern
Minor
5 months ago
—
2 years old
Unexpected use of comma operator
10562 : "string" == typeof M || (!1 === M && 0 < arguments.length)
10563 ? ((M = { url: M, data: e, dataType: t }),
10564 "function" == typeof r && (M.success = r))
10565 : void 0 === M && (M = {}),10566 (O = M.method || M.type || this.attr2("method")),
10567 (n =
10568 (n =Unexpected use of comma operator
10527 (o.clk_x = e.pageX - n.left),
10528 (o.clk_y = e.pageY - n.top))
10529 : ((o.clk_x = e.pageX - t.offsetLeft),
10530 (o.clk_y = e.pageY - t.offsetTop))),10531 setTimeout(function () {
10532 o.clk = o.clk_x = o.clk_y = null;
10533 }, 100);Unexpected use of comma operator
6203 o = (e.tabbable = {});
6204 t(o),
6205 (o.noConflict = function () {
6206 return (e.tabbable = n), o; 6207 });
6208 })());
6209})(this, function (e) {Unexpected use of comma operator
6201 (function () {
6202 var n = e.tabbable,
6203 o = (e.tabbable = {});
6204 t(o), 6205 (o.noConflict = function () {
6206 return (e.tabbable = n), o;
6207 });Unexpected use of comma operator
4334 : this.each(function () {
4335 var e, t, n, r;
4336 if (a) {
4337 (t = 0), (n = S(this)), (r = vt(i)); 4338 while ((e = r[t++]))
4339 n.hasClass(e) ? n.removeClass(e) : n.addClass(e);
4340 } else
Description
The comma operator includes multiple expressions where only one is expected. It evaluates each operand from left to right and returns the value of the last operand. However, this frequently obscures side effects, and its use is often an accident. Here are some examples of sequences:
Bad Practice
let a = (3, 5); // a = 5
a = b += 5, a + b;
while (a = next(), a && a.length);
(0, eval)("doSomething();");
res = doSomething(), val;
0, eval("doSomething();");
do {} while (doSomething(), !!test);
for (; doSomething(), !!test; );
if (doSomething(), !!test);
switch (val = func(), val) {}
while (val = func(), val < 42);
with (doSomething(), val) {}
Recommended
res = (doSomething(), val);
(0, eval)("doSomething();");
do {} while ((doSomething(), !!test));
for (i = 0, j = 10; i < j; i++, j--);
if ((doSomething(), !!test));
switch ((val = func(), val)) {}
while ((val = func(), val < 42));
with ((doSomething(), val)) {}