js 保留n位小数

//保留两位小数的方法start

function toDecimal2(x){

var f = parseFloat(x);

if(isNaN(f)){

return false;

}

var f = Math.round(x*100)/100;

var s = f.toString();

var rs = s.indexOf(‘.’);

//如果s中没有’.’返回-1

if(rs<0){

rs = s.length;

s += ‘.’;

}

while (s.length<=rs+2)

{

s += ‘0’;

}

return s;

}

//保留四位小数的方法

function toDecimal4(x){

var f = parseFloat(x);

if(isNaN(f)){

return false;

}

var f = Math.round(x*10000)/10000;

var s = f.toString();

var rs = s.indexOf(‘.’);

//如果s中没有’.’返回-1

if(rs<0){

rs = s.length;

s += ‘.’;

}

while (s.length<=rs+4)

{

s += ‘0’;

}

return s;

}