收集常用的正则表达式，欢迎补充。

1.匹配IP地址

function isIP(value){return /^((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){3}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})$/i.test(value);
}

2.匹配URL

function isURL(value){return /^((http|https):\/\/(\w+:{0,1}\w*@)?(\S+)|)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?$/.test(value);
}

3.匹配全汉字

function isChina(value){return /^[\u4E00-\u9FA3]{1,}$/.test(value);
}

4.匹配身份证号码

function isIDCard(value){return /(^\d{15}$)|(^\d{18}$)|(^\d{17}(\d|X|x)$)/.test(value);
}

5.匹配手机号码

function isPhoneNum(value){return /^0?(13[0-9]|15[012356789]|18[0236789]|14[57])[0-9]{8}$/.test(value);
}

6.匹配邮箱

function isEmail(value){return /^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))$/i.test(value);
}

7.匹配数字

function isNum(value){return /^-?(?:\d+|\d{1,3}(?:,\d{3})+)?(?:\.\d+)?$/.test(value);
}

8.匹配日期

function isDate(value){return !/Invalid|NaN/.test(new Date(value).toString());
}

9.匹配字母和下划线开头，允许n-m字节，允许字母数字下划线

function isAccountValid(value,m,n){var _n = n-1, _m = m-1;return new RegExp("^[a-zA-Z_][a-zA-Z0-9_]{"+_n+","+_m+"}$").test(value);
}

调用方法：

var isEmail = isEmail($("#input1").val());alert(isEmail);//true or false

以上的表达式均返回true or false。true为真，false为假。欢迎补充