深拷贝
- copyElement 简单类型(非对象)直接返回
- 缓存里面有没有,有直接返回
- copyType Boolean Date等
return new source.constructor(source.valueOf());
- RegExp:
new RegExp(source.source, source.toString().match(/[^/]*$/)[0])
- cloneNode: 是dom
return source.cloneNode(true);
- 数组或对象:
destination = isArray(source) ? [] : Object.create(getPrototypeOf(source));
- copyRecurse 递归:如果是数组或者对象执行for循环或for in循环。
var toString = Object.prototype.toString,
getPrototypeOf = Object.getPrototypeOf;
var isArray = Array.isArray;
function isObject(value) {
// http://jsperf.com/isobject4
return value !== null && typeof value === 'object';
}
function isValidObjectMaxDepth(maxDepth) {
return isNumber(maxDepth) && maxDepth > 0;
}
function isBlankObject(value) {
return value !== null && typeof value === 'object' && !getPrototypeOf(value);
}
function isFunction(value) {return typeof value === 'function';}
function isNumber(value) {return typeof value === 'number';}
function copy(source, destination, maxDepth) {
var stackSource = [];
var stackDest = [];
maxDepth = isValidObjectMaxDepth(maxDepth) ? maxDepth : NaN;
if (destination) {
stackSource.push(source);
stackDest.push(destination);
return copyRecurse(source, destination, maxDepth);
}
return copyElement(source, maxDepth);
function copyRecurse(source, destination, maxDepth) {
maxDepth--;
if (maxDepth < 0) {
return '...';
}
var key;
if (isArray(source)) {
for (var i = 0, ii = source.length; i < ii; i++) {
destination.push(copyElement(source[i], maxDepth));
}
} else if (isBlankObject(source)) {
// createMap() fast path --- Safe to avoid hasOwnProperty check because prototype chain is empty
for (key in source) {
destination[key] = copyElement(source[key], maxDepth);
}
} else if (source && typeof source.hasOwnProperty === 'function') {
// Slow path, which must rely on hasOwnProperty
for (key in source) {
if (source.hasOwnProperty(key)) {
destination[key] = copyElement(source[key], maxDepth);
}
}
} else {
// Slowest path --- hasOwnProperty can't be called as a method
for (key in source) {
if (hasOwnProperty.call(source, key)) {
destination[key] = copyElement(source[key], maxDepth);
}
}
}
return destination;
}
function copyElement(source, maxDepth) {
// Simple values
if (!isObject(source)) {
return source;
}
// Already copied values
var index = stackSource.indexOf(source);
if (index !== -1) {
return stackDest[index];
}
var needsRecurse = false;
var destination = copyType(source);
if (destination === undefined) {
destination = isArray(source) ? [] : Object.create(getPrototypeOf(source));
needsRecurse = true;
}
stackSource.push(source);
stackDest.push(destination);
return needsRecurse
? copyRecurse(source, destination, maxDepth)
: destination;
}
function copyType(source) {
switch (toString.call(source)) {
case '[object Int8Array]':
case '[object Int16Array]':
case '[object Int32Array]':
case '[object Float32Array]':
case '[object Float64Array]':
case '[object Uint8Array]':
case '[object Uint8ClampedArray]':
case '[object Uint16Array]':
case '[object Uint32Array]':
return new source.constructor(copyElement(source.buffer), source.byteOffset, source.length);
case '[object ArrayBuffer]':
// Support: IE10
if (!source.slice) {
// If we're in this case we know the environment supports ArrayBuffer
/* eslint-disable no-undef */
var copied = new ArrayBuffer(source.byteLength);
new Uint8Array(copied).set(new Uint8Array(source));
/* eslint-enable */
return copied;
}
return source.slice(0);
case '[object Boolean]':
case '[object Number]':
case '[object String]':
case '[object Date]':
return new source.constructor(source.valueOf());
case '[object RegExp]':
var re = new RegExp(source.source, source.toString().match(/[^/]*$/)[0]);
re.lastIndex = source.lastIndex;
return re;
case '[object Blob]':
return new source.constructor([source], {type: source.type});
}
if (isFunction(source.cloneNode)) {
return source.cloneNode(true);
}
}
}