Comments (2)
实现 _.get
function get(source, path, defaultValue = undefined) {
const paths = Array.isArray(path)
? path
: path.replaceAll('[', '.').replaceAll(']', '').split('.');
let curNode = source;
let curPath = paths.shift();
while (curPath && curNode) {
curNode = curNode[curPath];
curPath = props.shift();
}
return curNode === undefined ? defaultValue : curNode;
}
const obj = {
a: {
b: {
c: [1, 2, 3]
}
}
};
console.log(get(obj, 'a.b.c')); // [1,2,3]
console.log(get(obj, 'a.b.c.0')); // 1
console.log(get(obj, 'a.b.c[1]')); // 2
console.log(get(obj, ['a', 'b', 'c', '2'])); // 3
console.log(get(obj, 'a.b.c[3]')); // undefined
console.log(get(obj, 'a.c', 'bfe')); // 'bfe'
或者
function get(source, path, defaultValue = undefined) {
// your code here
const parts = Array.isArray(path) ? path : path
.replaceAll("[", ".")
.replaceAll("]", "")
.split(".")
if (parts.length === 0) {
return defaultValue
}
for (const part of parts) {
if (source[part] === undefined) {
return defaultValue
}
source = source[part]
}
return source
}
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实现 set
const obj = {
a: {
b: {
c: [1,2,3]
}
}
}
set(obj, 'a.b.c', 'BFE')
console.log(obj.a.b.c) // "BFE"
set(obj, 'a.b.c.0', 'BFE')
console.log(obj.a.b.c[0]) // "BFE"
set(obj, 'a.b.c[1]', 'BFE')
console.log(obj.a.b.c[1]) // "BFE"
set(obj, ['a', 'b', 'c', '2'], 'BFE')
console.log(obj.a.b.c[2]) // "BFE"
set(obj, 'a.b.c[3]', 'BFE')
console.log(obj.a.b.c[3]) // "BFE"
set(obj, 'a.c.d[0]', 'BFE')
// valid digits treated as array elements
console.log(obj.a.c.d[0]) // "BFE"
set(obj, 'a.c.d.01', 'BFE')
// invalid digits treated as property string
console.log(obj.a.c.d['01']) // "BFE"
function set(obj, path, value) {
path = Array.isArray(path) ? path : path.replace('[', '.').replace(']', '').split('.');
src = obj;
path.forEach((key, index, array) => {
if (index == path.length - 1) {
src[key] = value;
} else {
if (!src.hasOwnProperty(key)) { // if the key doesn't exist on object
const next = array[index + 1];
src[key] = String(Number(next)) === next ? [] : {}; // create a new object if next is item in array is not a number
}
src = src[key];
}
})
}
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