比较版本号大小

function compareVersion(x,y){
    let xArr = x.split('.'),
    yArr = y.split('.'),
    len = xArr.length > yArr.length ? xArr.length : yArr.length;
    for(let i = 0;i < len;i++){
        let xItem =  xArr[i],yItem = yArr[i];
        if(xItem > yItem){
            return 1
        }else if(xItem < yItem){
            return -1
        }
    }
    return 0
}