reset regex javascript

How to Reset RegEx in Javascript#

RegEx, or regular expressions, are a powerful tool in Javascript for matching and manipulating strings. However, sometimes we may need to reset or clear the RegEx pattern we have set in our code. Here are three ways to do so:

Method 1: Assigning an Empty RegEx Pattern#

The simplest way to reset a RegEx pattern in Javascript is by assigning an empty pattern to the variable or expression that contains it.

let myRegEx = /hello/;
console.log(myRegEx.test("hello world")); // true

myRegEx = //;
console.log(myRegEx.test("hello world")); // true
    

In the example above, we first define a RegEx pattern for the string "hello". We test it with the string "hello world" and get a true result. Then, we assign an empty pattern to the same variable, effectively resetting it, and test again with the same string, getting the same true result.

Method 2: Using the RegExp Constructor#

We can also reset a RegEx pattern using the RegExp constructor, which creates a new RegEx object with the specified pattern. If no pattern is provided, an empty pattern is used by default.

let myRegEx = /hello/;
console.log(myRegEx.test("hello world")); // true

myRegEx = new RegExp();
console.log(myRegEx.test("hello world")); // true
    

In this example, we do the same as before, but instead of assigning an empty pattern directly, we create a new RegEx object using the RegExp constructor without any arguments.

Method 3: Using the RegEx.prototype.compile() Method#

The third way to reset a RegEx pattern is by using the compile() method of the RegEx object. This method recompiles the pattern of the object with a new string, effectively resetting it. It also allows us to set additional flags for the pattern.

let myRegEx = /hello/;
console.log(myRegEx.test("hello world")); // true

myRegEx.compile("");
console.log(myRegEx.test("hello world")); // true
    

Here, we first define a RegEx pattern for the string "hello". We test it with the string "hello world" and get a true result. Then, we use the compile() method to reset the pattern to an empty string. We test again with the same string and get the same true result.