vue broadcast和dispatch

function broadcast(componentName, eventName, params) {
this.$children.forEach((child) => {
const name = child.$options.componentName;

if (name === componentName) {
child.$emit(...[eventName].concat(params));
} else {
broadcast.apply(child, [componentName, eventName].concat([params]));
}
});
}
export default {
methods: {
dispatch(componentName, eventName, params) {
let parent = this.$parent || this.$root;
let name = parent.$options.componentName;

while (parent && (!name || name !== componentName)) {
parent = parent.$parent;

if (parent) {
name = parent.$options.componentName;
}
}
if (parent) {
parent.$emit(...[eventName].concat(params));
}
},
broadcast(componentName, eventName, params) {
broadcast.call(this, componentName, eventName, params);
},
},
};