十一、实现节流功能
核心要点:
如果在定时器的时间范围内再次触发,则不予理睬,等当前定时器完成,才能启动下一个定时器。
const throttle = (fn, delay = 500) => {
let flag = true;
return (...args) => {
if (!flag) return;
flag = false;
setTimeout(() => {
fn.apply(this, args);
flag = true;
}, delay);
};
};
const clone = parent => {
// 判断类型
const isType = (target, type) => `[object ${type}]` === Object.prototype.toString.call(target)
// 处理正则
const getRegExp = re => {
let flags = "";
if (re.global) flags += "g";
if (re.ignoreCase) flags += "i";
if (re.multiline) flags += "m";
return flags;
};
const _clone = parent => {
if (parent === null) return null;
if (typeof parent !== "object") return parent;
let child, proto;
if (isType(parent, "Array")) {
// 对数组做特殊处理
child = [];
} else if (isType(parent, "RegExp")) {
// 对正则对象做特殊处理
child = new RegExp(parent.source, getRegExp(parent));
if (parent.lastIndex) child.lastIndex = parent.lastIndex;
} else if (isType(parent, "Date")) {
// 对Date对象做特殊处理
child = new Date(parent.getTime());
} else {
// 处理对象原型
proto = Object.getPrototypeOf(parent);
// 利用Object.create切断原型链
child = Object.create(proto);
}
for (let i in parent) {
// 递归
child[i] = _clone(parent[i]);
}
return child;
};
return _clone(parent);
};