1.写一个方法将数组换成前端更易解析的树状结构
function
getTree(data) {
var
newData = [],
hash = {};
for
(
var
i = 0; i < data.length; i++) {
if
(!hash[data[i].province]) {
hash[data[i].province] = {
‘province‘
: data[i].province
};
hash[data[i].province][
‘city‘
] = [{
‘name‘
: data[i].city,
‘code‘
: data[i].code
}]
newData.push(hash[data[i].province]);
}
else
if
(hash[data[i].province].province == data[i].province) {
hash[data[i].province][
‘city‘
].push({
‘name‘
: data[i].city,
‘code‘
: data[i].code
})
}
}
return
newData;
}
var
data = [{
‘province‘
:
‘浙江‘
,
‘city‘
:
‘温州‘
,
‘code‘
:
‘10010‘
}, {
‘province‘
:
‘浙江‘
,
‘city‘
:
‘杭州‘
,
‘code‘
:
‘10011‘
}, {
‘province‘
:
‘安徽‘
,
‘city‘
:
‘合肥‘
,
‘code‘
:
‘10012‘
}, {
‘province‘
:
‘安徽‘
,
‘city‘
:
‘马鞍山‘
,
‘code‘
:
‘10013‘
}, {
‘province‘
:
‘浙江‘
,
‘city‘
:
‘宁波‘
,
‘code‘
:
‘10014‘
}];
console.log(getTree(data));
2.统计字符串出现最多的字母
function getMax(str) { var hash = {}, maxstr, max = 1; for (var i = 0; i < str.length; i++) { if (!hash[str[i]]) { hash[str[i]] = 1; } else { hash[str[i]]++; } if (hash[str[i]] > max) { max = hash[str[i]]; maxstr = str[i]; } } return maxstr; } var str = ‘abcdeffggghhhhiiiii‘; console.log(getMax(str));
3.排序算法
function bubbleSort(arr) { for (var i = 0; i < arr.length; i++) { for (var j = 0; j < arr.length - i - 1; j++) { if (arr[j] < arr[j + 1]) { var temp = arr[j + 1]; arr[j + 1] = arr[j]; arr[j] = temp; } } } return arr; } var arr = [1, 2, 8, 3, 4, 1]; console.log(bubbleSort(arr));
4.去重算法
function unique1(arr) { var newArr = []; for (var i = 0; i < arr.length; i++) { if (newArr.indexOf(arr[i]) == -1) { newArr.push(arr[i]); } } return newArr; } var arr1 = [‘b‘, ‘b‘, ‘a‘, 1, 3, 4, 4]; console.log(unique1(arr1)); function unique2(arr) { var hash = {}, newArr = []; for (var i = 0; i < arr.length; i++) { if (!hash[arr[i]]) { hash[arr[i]] = true; newArr.push(arr[i]); } } return newArr; } var arr2 = [‘b‘, ‘b‘, ‘a‘, 1, 3, 4, 4]; console.log(unique2(arr2)); function unique3(arr) { for (var i = 0; i < arr.length; i++) { for (var j = 0; j < arr.length; j++) { if (arr[i] === arr[j] && i != j) { arr.splice(i, 1); } } } return arr; } var arr3 = [‘b‘, ‘b‘, ‘a‘, 1, 3, 4, 4]; console.log(unique3(arr3));
5.二分查找算法(建立在已经排好序的情况下)
function binarySearch(arr, data) { var end = arr.length - 1, start = 0; while (start <= end) { var middle = Math.floor((start + end) / 2); if (arr[middle] > data) { end = middle - 1; } else if (arr[middle] < data) { start = middle + 1; } else { return middle; } } return -1; } var arr = [1, 2, 3, 4, 5, 6]; console.log(binarySearch(arr, 2));
原文地址:https://www.cnblogs.com/TigerZhang-home/p/9678781.html