js面试题分享

数组去重

数字数组

const arr1 = [1,2,3,4.4,32,121,4,5,5,6,2]
function arrayUnique(array) {
	return Array.from(new Set(arr1));
}
console.log(arrayUnique(arr1)); // [1, 2, 3, 4.4, 32, 121, 4, 5, 6]
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数组对象去重

• 方案1

  const arr2 = [
  	{ name: 'a1', value: 1 },
  	{ name: 'a2', value: 1 },
  	{ name: 'a3', value: 1 },
  	{ name: 'a4', value: 1 },
  	{ name: 'a4', value: 1 },
  	{ name: 'a3', value: 1 },
  	{ name: 'a2', value: 1 },
  	{ name: 'a1', value: 1 },
  ];
  function arrayUnique(array, str) {
  	let obj = {};
  	return array.reduce((pre, cur) => {
  		obj[cur[str]] ? '' : obj[cur[str]] = pre.push(cur);
  		return pre;
  	}, [])
  }
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• 方案2

  const arr2 = [
  	{ name: 'a1', value: 1 },
  	{ name: 'a2', value: 1 },
  	{ name: 'a3', value: 1 },
  	{ name: 'a4', value: 1 },
  	{ name: 'a4', value: 1 },
  	{ name: 'a3', value: 1 },
  	{ name: 'a2', value: 1 },
  	{ name: 'a1', value: 1 },
  ];
  function arrayUnique(array, str) {
  	let map = new Map();
  	array.forEach(ele => {
  		map.set(ele[str], ele);
  	});
  	return [...map.values()]
  }
  console.log(arrayUnique(arr2, 'name'));
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给定一个url，转为location对象

const url1 = 'https://www.baidu.com/s?ie=utf-8&f=8&rsv_bp=1&rsv_idx=1&tn=baidu&wd=mapbox';

function createLocationObj(str) {
	let obj = {};
	const a1 = url1.split('://')
	obj['protocol'] = a1[0];
	let b;
	if (a1[1].includes(':')) {
		const a2 = a1[1].split(':');
		obj['hostname'] = a2[0];
		b = a2[1].split('/');
		obj['port'] = b[0]
	} else {
		b = a1[1].split('/');
		obj['hostname'] = b[0];
		obj['port'] = obj.protocol === 'https' ? '443' : '8080';
	}
	const a3 = b[1].split('?');
	obj['pathname'] = `/${a3[0]}`;
	const a4 = a3[1].split('&');
	let _params = {};
	a4.forEach(ele => {
		const a5 = ele.split('=');
		_params[a5[0]] = a5[1]
	});
	obj['query'] = _params;
	return obj;
}
console.log('-', createLocationObj(url1));
// {
// 	hostname: "www.baidu.com"
// 	pathname: "/s"
// 	port: "443"
// 	protocol: "https"
// 	query: {
// 		f: "8"
// 		ie: "utf-8"
// 		rsv_bp: "1"
// 		rsv_idx: "1"
// 		tn: "baidu"
// 		wd: "mapbox"
// 	}
// }
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