格式化数值，千分号

formatInt(v){
    // 1234567890 => "1,234,567,890"
    return (v+"").replace(/(\d)(?=(?:\d{3})+$)/g, '$1,')
},
formatFloat(v){
    // 1234567890.1234 => "1,234,567,890.1234"
    return (v+"").replace(/(\d)(?=(\d{3})+\.)/g, '$1,')
},
formatFloatEx(v,length){
    // length=2 1234567890.1234 => "1,234,567,890.12"
    return v.toFixed(length).replace(/(\d)(?=(\d{3})+\.)/g, '$1,')
},
formatJPercent(v){
    // 0.66888 => 66.89%
    return (v*100).toFixed(2)+'%';
}