Valid Parentheses Matcher

Arguments

sstring

A string containing only the characters ()[]{}.

Returns

boolean — true when every opener is matched by the correct closer in order, else false.

Examples

isValidParentheses("()[]{}"); // true
isValidParentheses("{[]}");    // true
isValidParentheses("");        // true — the empty string is vacuously valid

isValidParentheses("(]");   // false — wrong closer type
isValidParentheses("([)]"); // false — correct types, wrong order
isValidParentheses("(");    // false — unclosed opener left on the stack

What it has to do

• Return true if string brackets are valid, false otherwise.
• Use Stack data structure.

Notes

• After the loop finishes, the stack must be empty — a non-empty stack means openers were never closed.
• Encountering a closer while the stack is empty is an immediate false; otherwise .pop() on [] returns undefined and can mask bugs.