有如下多层嵌套的对象:
var obj = { l1: { l2: { l3: "Hello World" } }}
方法1:
var r = (((obj || {}).l1 || {}).l2 || {}).l3;
或
var r = obj.l1 && obj.l1.l2 && obj.l1.l2.l3
方法2:
let delve = (obj, key) => (key.split('.').map(p => (obj = obj && obj[p])), obj);console.log(delve(obj, 'l1.l2.l3')); // Hello World
方法3:
function checkNested(obj, key, ...rest) { if (obj === undefined || obj === null) return false; if (rest.length == 0 && obj.hasOwnProperty(key)) return true; return checkNested(obj[key], ...rest);}console.log(checkNested(obj, 'l1', 'l2', 'l3')); // true
方法4:
function validChain(obj, ...keys) { return keys.reduce((obj, key) => (obj || {})[key], obj) !== undefined}console.log(validChain(obj, 'l1', 'l2', 'l3')); // true
方法5:
function objHasKeys(obj, keys) { var next = keys.shift(); return obj[next] && (! keys.length || objHasKeys(obj[next], keys));}
如果有更好的方式,欢迎补充????。