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snabbdom/modules/eventlisteners.js

102 lines
2.7 KiB
JavaScript

function invokeHandler(handler, vnode, event) {
if (typeof handler === "function") {
// call function handler
handler.call(vnode, event, vnode);
} else if (typeof handler === "object") {
// call handler with arguments
if (typeof handler[0] === "function") {
// special case for single argument for performance
if (handler.length === 2) {
handler[0].call(vnode, handler[1], event, vnode);
} else {
var args = handler.slice(1);
args.push(event);
args.push(vnode);
handler[0].apply(vnode, args);
}
} else {
// call multiple handlers
for (var i = 0; i < handler.length; i++) {
invokeHandler(handler[i]);
}
}
}
}
function handleEvent(event, vnode) {
var name = event.type,
on = vnode.data.on;
// call event handler(s) if exists
if (on && on[name]) {
invokeHandler(on[name], vnode, event);
}
}
function createListener() {
return function handler(event) {
handleEvent(event, handler.vnode);
}
}
function updateEventListeners(oldVnode, vnode) {
var oldOn = oldVnode.data.on,
oldListener = oldVnode.listener,
oldElm = oldVnode.elm,
on = vnode && vnode.data.on,
elm = vnode && vnode.elm,
name;
// optimization for reused immutable handlers
if (oldOn === on) {
return;
}
// remove existing listeners which no longer used
if (oldOn && oldListener) {
// if element changed or deleted we remove all existing listeners unconditionally
if (!on) {
for (name in oldOn) {
// remove listener if element was changed or existing listeners removed
oldElm.removeEventListener(name, oldListener, false);
}
} else {
for (name in oldOn) {
// remove listener if existing listener removed
if (!on[name]) {
oldElm.removeEventListener(name, oldListener, false);
}
}
}
}
// add new listeners which has not already attached
if (on) {
// reuse existing listener or create new
var listener = vnode.listener = oldVnode.listener || createListener();
// update vnode for listener
listener.vnode = vnode;
// if element changed or added we add all needed listeners unconditionally
if (!oldOn) {
for (name in on) {
// add listener if element was changed or new listeners added
elm.addEventListener(name, listener, false);
}
} else {
for (name in on) {
// add listener if new listener added
if (!oldOn[name]) {
elm.addEventListener(name, listener, false);
}
}
}
}
}
module.exports = {
create: updateEventListeners,
update: updateEventListeners,
destroy: updateEventListeners
};