Update parseInterval to handle "0" correctly (#1835)

* Update parseInterval to handle "0" correctly

When a parameter like "0ms" is passed in to parseInterval it gets parsed to 0.
Previously this would result in a return value of "undefined" because 0 is falsy
and thus the `return 0 || undefined` statements return undefined.

The purpose of the form `parseFloat(str) || undefined` was to return "undefined" if
parseFloat failed (parseFloat returns NaN, a falsy value, if it can't parse its
argument). Unfortunately, as mentioned, parseFloat can also succeed and return a
falsy value -- when the argument is "0" (or "0.0", etc.). So the new code, rather
than depending on the falsiness of the result of parseFloat, explicitly checks for
a NaN.

* Adds some semicolons

Adds some semicolons to parseInterval (and tests) for consistency.

* Add one more parseInterval test for "0"

Adds test test to make sure parseInterval works on "0".

* Adds functional tests for every, swap, settle, throttle, and delay

* Explcitly check that setTimeout values are > 0

These values come from user settings that are read from parseInterval,
so they could be a number or undefined.

If the value being checked is > 0 setTimeout will be called with some
associated function. If the value is 0 or 'undefined' the associated function
will be called immediately ('undefined' is not greater than 0).

* Change '!== undefined' to '> 0'

`pollInterval !== undefined` is a subtly different conditional than just `pollInterval` or `pollInterval > 0` (which are equivalent). Changes the conditional to `pollInterval > 0` so as to not change the behavior but also be more explicit in the test.

1 files changed, 15 insertions, 13 deletions

diff --git a/src/htmx.js b/src/htmx.js
index 2bb58239..7861ae84 100644
--- a/src/htmx.js
+++ b/src/htmx.js
@@ -148,18 +148,20 @@ return (function () {
 
         function parseInterval(str) {
             if (str == undefined)  {
-                return undefined
+                return undefined;
             }
+
+            let interval = NaN;
             if (str.slice(-2) == "ms") {
-                return parseFloat(str.slice(0,-2)) || undefined
-            }
-            if (str.slice(-1) == "s") {
-                return (parseFloat(str.slice(0,-1)) * 1000) || undefined
-            }
-            if (str.slice(-1) == "m") {
-                return (parseFloat(str.slice(0,-1)) * 1000 * 60) || undefined
+                interval = parseFloat(str.slice(0, -2));
+            } else if (str.slice(-1) == "s") {
+                interval = parseFloat(str.slice(0, -1)) * 1000;
+            } else if (str.slice(-1) == "m") {
+                interval = parseFloat(str.slice(0, -1)) * 1000 * 60;
+            } else {
+                interval = parseFloat(str);
             }
-            return parseFloat(str) || undefined
+            return isNaN(interval) ? undefined : interval;
         }
 
         /**
@@ -1538,14 +1540,14 @@ return (function () {
                             return;
                         }
 
-                        if (triggerSpec.throttle) {
+                        if (triggerSpec.throttle > 0) {
                             if (!elementData.throttle) {
                                 handler(elt, evt);
                                 elementData.throttle = setTimeout(function () {
                                     elementData.throttle = null;
                                 }, triggerSpec.throttle);
                             }
-                        } else if (triggerSpec.delay) {
+                        } else if (triggerSpec.delay > 0) {
                             elementData.delayed = setTimeout(function() { handler(elt, evt) }, triggerSpec.delay);
                         } else {
                             triggerEvent(elt, 'htmx:trigger')
@@ -1822,7 +1824,7 @@ return (function () {
                     handler(elt);
                 }
             }
-            if (delay) {
+            if (delay > 0) {
                 setTimeout(load, delay);
             } else {
                 load();
@@ -1881,7 +1883,7 @@ return (function () {
                 if (!maybeFilterEvent(triggerSpec, elt, makeEvent("load", {elt: elt}))) {
                                 loadImmediately(elt, handler, nodeData, triggerSpec.delay);
                             }
-            } else if (triggerSpec.pollInterval) {
+            } else if (triggerSpec.pollInterval > 0) {
                 nodeData.polling = true;
                 processPolling(elt, handler, triggerSpec);
             } else {