使用正则表达式格式化金额

var val='12312.235423'
var rex = /\d{1,3}(?=(\d{3})+$)/g
val.replace(/^(-?)(\d+)((\.\d+)?)$/, function (s, s1, s2, s3) {
    return '$' + s1 + s2.replace(rex, '$&,') + s3
})

//"$12,312.235423"

String.prototype.replace()