How to use Regular Expression In Javascript

In this method we employ expressions to repeatedly remove valid pairs of parentheses until none remain.

Define an expression pattern that matches pairs of parentheses.
Enter into a loop that finds and removes pairs using replace operations with a string as replacement text.
Repeat step 2 until no valid pairs can be found in iterations (i.e. after performing replacements without finding any matches).
If, after completing these iterations our initial string becomes empty it means all parentheses have been successfully matched and eliminated; thus return true. Otherwise return false.

Syntax:

/pattern/modifiers;

Javascript

function isValidParentheses(str) {
    const regex = /(\(\)|\[\]|\{\})/g;

    while (str.match(regex)) {
        str = str.replace(regex, "");
    }

    return str.length === 0;
}

const inputString = "{[()]]}";
console.log(
    `Is it a valid Paranthesis ?
${isValidParentheses(inputString)}`
);

Output

Is it a valid Paranthesis ?
false

JavaScript Program to Check Valid Parentheses Using String

In this article, we will learn how we can check valid parentheses of a string, and write a program to check whether the pairs and order of “{ “, ” } “, “(“, “)”, “[“, “]” in the string expression is right or not.

Example:

Input: exp = "[()][()()]()" 
Output: True.
Explanation: all of the brackets are properly formed.
Input: exp = "[(])"
Output: False
Explanation: The first and fourth brackets are not balanced because there is a closing ']' before the final '('.