Reference · Browser

js_has

js_has(str) -> bool

What it does

Whether the page has a feature, by its dotted name, without calling it: true if each part of "navigator.vibrate" is there, false if any is not. js("navigator.vibrate") would call it; this only looks. On the server, where there is no page, it is false.

Examples

component Buzz() {    state can = false    can = js_has("navigator.vibrate")    <button disabled={!can} @click={() => { js("navigator.vibrate", 200) }}>Buzz</button>}

print(js_has("navigator.vibrate"), js_has("no.such.thing"))

false false

Edge cases

• A property that is there with the value undefined counts as not there.
• A part that is null ends it: js_has("a.b") with a null is false, not an error.
• It reads only what is reached by name from the page's globals, as js does.

Errors

The name must be text: anything else is an error.

Chaining

"Notification" | js_has reads as js_has("Notification").

See also

js, js_new, platform

Edit this page on GitHub · every example's output was made by running it (tools/refcheck.mjs) · questions on Discord or r/quillo