Will Anderson
42 lines
1.4 KiB
EmacsLisp
42 lines
1.4 KiB
EmacsLisp
// browser-counter.el — canonical browser DOM bridge example
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//
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// Compile with: elc --target=js examples/browser-counter.el > counter.js
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//
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// Then include in an HTML page that has a <span id="count-display"> element.
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// The page can call window.increment() from any onclick handler, e.g.:
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// <button onclick="increment()">+1</button>
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//
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// On load the display is initialised to "0". Each call to increment()
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// adds 1 and updates the display text.
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//
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// Demonstrates:
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// - dom_get_element to locate a DOM node by id
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// - dom_set_text to update visible text content
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// - dom_is_null to guard against missing elements
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// - window_set to expose an El function for inline event handlers
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// - state_set/get for in-memory counter state (survives calls, resets
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// on page reload — same semantics as the C state_* API)
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fn init() -> Void {
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state_set("counter", 0)
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let display = dom_get_element("count-display")
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if !dom_is_null(display) {
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dom_set_text(display, "0")
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}
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}
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fn increment() -> Void {
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let current = str_to_int(state_get("counter"))
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let next = current + 1
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state_set("counter", next)
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let display = dom_get_element("count-display")
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if !dom_is_null(display) {
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dom_set_text(display, int_to_str(next))
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}
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}
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fn main() -> Void {
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init()
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window_set("increment", increment)
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}
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