AlgoDaily - Implement JSON.parse

One Pager Cheat Sheet

You can implement your own version of the JSON.parse() method, called parseJSON, that accepts one parameter and can return one of the following: array, object, string, number, boolean, or null.
By defining multiple if cases to check for null, empty objects, arrays or booleans and additional parsing of values inside quotes and brackets, we can create a JSON Parser in JavaScript.

This is our final solution.

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}
 
function parseJSON(input) {
​
    // if the input is empty or starts with an invalid character, throw an error
    if (input === "" || input[0] === "'") {
        throw Error();
    }
​
    // check if the input is null, an empty object, empty array, or a boolean and return the value from the input
    if (input === "null") {
        return null;
    }
    if (input === "{}") {
        return {};
    }
    if (input === "[]") {
        return [];
    }
    if (input === "true") {
        return true;
    }
    if (input === "false") {
        return false;
    }
​
    //if the input starts with a quote, return the value from inside the quotes
    if (input[0] === '"') {
        return input.slice(1, -1);
    }
​
    // if it starts with a bracket, perform parsing of the contents within the brackets
    if (input[0] === "{") {
        return input

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One Pager Cheat Sheet

This is our final solution.

That's all we've got! Let's move on to the next tutorial.

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