/* 浅拷贝 */
function extend(parent, child) {
var i;
child = child || {};
for (i in parent) {
if (parent.hasOwnProperty(i)) {
child[i] = parent[i];
}
}
return child;
} var dad = { name: "Adam" };
var kid = extend(dad);
console.log(kid.name); // "Adam" var dad = {
counts: [1, 2, 3],
reads: { paper: true }
};
var kid = extend(dad);
kid.counts.push(4);
console.log(dad.counts.toString()); // "1,2,3,4"
console.log(dad.reads === kid.reads); // true

存在问题:你可以发现dad和kid的reads是一样的,也就是他们使用的是同一个引用,这也就是浅拷贝带来的问题。

/* 深拷贝 */
function extendDeep(parent, child) {
var i,
toStr = Object.prototype.toString,
astr = "[object Array]"; child = child || {}; for (i in parent) {
if (parent.hasOwnProperty(i)) {
if (typeof parent[i] === 'object') {
child[i] = (toStr.call(parent[i]) === astr) ? [] : {};
extendDeep(parent[i], child[i]);
} else {
child[i] = parent[i];
}
}
}
return child;
} var dad = {
counts: [1, 2, 3],
reads: { paper: true }
};
var kid = extendDeep(dad); kid.counts.push(4);
console.log(kid.counts.toString()); // "1,2,3,4"
console.log(dad.counts.toString()); // "1,2,3" console.log(dad.reads === kid.reads); // false
kid.reads.paper = false;

深拷贝以后,两个值就不相等了,bingo!

05-11 19:54
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