match（）函数输入的TypeScript“类型”是什么

Question

Javascript String Match function

From the above documentation I see that the input to the String.prototype.match() function is "regexp". It's obviously not a string. What is its type?

In TypeScript how can I declare the input variable?

regex:regexp = ^\d{2}\/\d{2}\/\d{4}$

The above obviously throws an error as regexp is not a recognized type. How can I fix it?

Answer 1

You can look at the type information in lib.d.ts :

/**
  * Matches a string with a regular expression, and returns an array containing the results of that search.
  * @param regexp A variable name or string literal containing the regular expression pattern and flags.
  */
match(regexp: string): RegExpMatchArray;

/**
  * Matches a string with a regular expression, and returns an array containing the results of that search.
  * @param regexp A regular expression object that contains the regular expression pattern and applicable flags.
  */
match(regexp: RegExp): RegExpMatchArray;

You can see that the type for a regular expression is RegExp , and there are two definitions for match , one taking a string, the other a RegExp.

Answer 2

Try this

//inside the class
//this expression is to test valid email

public reg: RegExp = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;

and then you can test it in your class

this.reg.test("expression to test")

//out side the class

let reg = /^\d+$/;
alert(reg.test("sd")); //will alert false