res.js

/**
 * res.js
 * @authors Joe Jiang (hijiangtao@gmail.com)
 * @date    2017-04-03 20:42:30
 * @version $Id$
 * 
 * Problem: Write a function to find the longest common prefix string amongst an array of strings.
 * 
 * @param {string[]} strs
 * @return {string}
 */
let longestCommonPrefix = function(strs) {
	if (strs === '' || strs.length === 0) {
		return '';
	}

	let prefix = '',
		strslen = strs.length,
		strlen = strs[0].length;

	for (let i = 0; i < strlen; i++) {
		let jud = true;

		for (let j = 1; j < strslen; j++) {
			if (strs[j][i] === undefined || strs[j][i] !== strs[0][i]) {
				jud = false;
				break;
			}
		}

		if (jud) {
			prefix += strs[0][i];
		} else {
			return prefix;
		}
	}

	return prefix;
};

/**
 * Another solution: Sort the array first, and then you can simply compare the first and last elements in the sorted array.
 * 
 */