字符的操作
var word = "hello world"
length字符串长度
let len = word.length
trim去掉空格
word.trim()
indexOf查找(找不到返回-1)
let index = word.indexOf("word")
let index = word.indexOf("or", 2)
charAt返回哪个位置的值
let result = word.charAt(3)
大小写转换
word.toUpperCase()
word.toLowerCase()
split字符串转数组
let list= word.split(" ")
let list= word.split(" ", 1)
concat字符串拼接
let person = "李公子"
let result = word.concat(person)
let result = word + person
字符串与数字互转
let num = 303
let str = num.toString()
let str = "123"
let num = parseInt(str)
replace字符串替换
var str = "我的名字叫:wxdev"
let result = str.replace("wxdev", "wxchatdev")
数组的操作
var persons = [
{name:"张三",age:23},
{name:"李四",age:21},
{name:"王五",age:23}
]
修改数据
persons[0].name = "张三丰"
splice删除数据
persons.splice(1, 1);
清空数据
persons = []
concat添加数组
let newpersons = [
{name:"赵公子",age:18}
]
persons = persons.concat(newpersons)
push末尾添加元素
let person = {name:"李公子",age:20}
persons.push(person)
unshift头部添加元素
let person = {name:"李公子",age:20}
persons.unshift(person)
pop删除末尾元素
persons.pop()
shift删除首个元素
persons.shift()
map函数(返回数组)
persons = persons.map(function(item, index) {
return (item.age + 1)
})
persons = persons.map(item => {
return (item.age + 1)
})
filter函数(条件过滤,返回数组)
let list = persons.filter(function(item) {
return (item.age > 20)
})
find函数(条件过滤,返回第一个数据)
let result = persons.find(function(item) {
return (item.age == 23)
})
foreach函数(遍历)
var list = []
persons.forEach(item => {
if (item.age == 21) {
list.push(item)
}
})
sort函数(排序)
persons.sort((a, b) => {
a.age.localeCompare(b.age)
})
join函数(数组转字符串)
let list = ["1", "2", "3"]
let liststring = list .join()
split函数(字符串转数组)
let string = "张三,李四、王五"
let stringlist = string.split(",")
reverse函数(倒序)
let list = ["1", "2", "3"]
list.reverse()
length数组元素数量
let count = persons.length
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