//将字母i全部替换成5

<script language="javascript">

var txt = "sjfisjfisdjfijsidfjioalfjewofjjgs";

alert(txt .replace(/i/g,"5"));

</script>

 

//只将第一个字母i替换成5

<script language="javascript">

var txt = "sjfisjfisdjfijsidfjioalfjewofjjgs";

alert(txt .replace("i","5"));

</script>

//将15，255.55替换为15255.55

parseFloat(num2.split(",").join(""));

//直接使用 FormatNumber(srcStr,nAfterDot); 这个方法就行了。

function FormatNumber(srcStr,nAfterDot){

        var srcStr,nAfterDot;

        var resultStr,nTen;

        srcStr = ""+srcStr+"";

        strLen = srcStr.length;

        dotPos = srcStr.indexOf(".",0);

        if (dotPos == -1){

            resultStr = srcStr+".";

            for (i=0;i<nAfterDot;i++){

                resultStr = resultStr+"0";

            }

            return resultStr;

        } else{

            if ((strLen - dotPos - 1) >= nAfterDot){

                nAfter = dotPos + nAfterDot + 1;

                nTen =1;

                for(j=0;j<nAfterDot;j++){

                nTen = nTen*10;

            }

            resultStr = Math.round(parseFloat(srcStr)*nTen)/nTen;

            return resultStr;

            } else{

                resultStr = srcStr;

                for (i=0;i<(nAfterDot - strLen + dotPos + 1);i++){

                    resultStr = resultStr+"0";

                }

                return resultStr;

            }

        }

    }