1.Number
let num = Number("111")
2.parseInt(转为整数)
let num = parseInt("111")
3.parseFloat
let num = parseFloat("111.11")
4. “+“运算符
let num = +"111.11"
5. “*“运算符
let num = "111.11"*1
let num = Number("111")
let num = parseInt("111")
let num = parseFloat("111.11")
let num = +"111.11"
let num = "111.11"*1