解析函数

function parse(obj = {a: [1, {b: 2}]}, path = 'a[1].b'){
    path = path.replace(/[/g,'.')
    path = path.replace(/]/g,'')
    let splitPath = path.split('.')
    let val = obj
    for(let i = 0;i < splitPath.length;i++){
        let item = splitPath[i]
        val = val && val[item]
    }
    return val
}