toFixed四舍五入不准的替代方法

//重写toFixed
Number.prototype.toFixed=function(s) {
    const adjust = this >= 0 ? 0.5 : -0.5;
    return (parseInt(this * Math.pow( 10, s ) + adjust)/ Math.pow( 10, s )).toString();
}
//toLocaleString
function format(num, decimals){
    return num.toLocaleString('en-US', {
        minimumFractionDigits: 2,      
        maximumFractionDigits: 2,
        useGrouping: false
    })
}
//或者Intl.NumberFormat
function format(num, decimals){
    const formatter = new Intl.NumberFormat('en-US', {
        minimumFractionDigits: decimals,      
        maximumFractionDigits: decimals,
        useGrouping: false
    })
    return formatter.format(num)
}