[英]How to create Dynamic Regular Expression in javascript to validate decimal number
I have to validate a decimal number based on the digits provided before the decimal and after the decimal. 我必须根据十进制之前和十进制之后提供的数字来验证十进制数字。 Say i have a function which is having a regular expression and takes two parameters as digits before the decimal and digits after the decimal. 说我有一个具有正则表达式的函数,并接受两个参数作为小数点前的数字和小数点后的数字。
function validateDecimalNo(digitBeforeDec,digitAfterDec){
//here i need to write the regular expression to validate the decimal no based on the inputs.
}
How to create the single dynamic regular expression to meet above requirement. 如何创建单个动态正则表达式来满足上述要求。
In JavaScript, you have literal syntax ( /regex/
, {object}
, or even "string"
), and you have the non-literal syntax ( new RegExp()
, new Object()
, new String()
). 在JavaScript中,您具有文字语法( /regex/
, {object}
甚至是"string"
),并且具有非文字语法( new RegExp()
, new Object()
和new String()
)。
With this provided, you can use the non-literal version of regex, which takes a string input: 借助此功能,您可以使用非文字版本的regex,该版本需要输入字符串:
var myRegex = new RegExp("hello", "i"); // -> /hello/i
So, this provided, we can make a function that creates a "dynamic regex" function (quotes because it's actually returning a new regex object every time it's run). 因此,提供了这一点,我们可以创建一个创建“动态正则表达式”函数的函数(引用,因为它实际上每次运行时都会返回一个新的正则表达式对象)。
For instance: 例如:
var getRegex = function(startingSym, endingSym, optional){
return new RegExp(startingSym + "(.+)" + endingSym, optional)
}
So, with this example function, we can use it like this: 因此,通过此示例函数,我们可以像这样使用它:
var testing = getRegex("ab", "cd", "i");
console.log(testing);
// Output:
/ab(.+)cd/i
Why use regexp? 为什么要使用regexp? Just check the number directly. 只需直接检查电话号码即可。
function make_decimal_validator(digitBeforeDec,digitAfterDec) {
return function(no) {
var parts = no.split('.');
if (parts.length !== 2) throw "Invalid decimal number";
return parts[0].length === digitBeforeDec && parts[1].length === digitAfterDec;
};
}
Make your validator: 使您的验证器:
var validator23 = make_decimal_validator(2, 3);
validator23('12.345') // true
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