Basic Object to JSON

• A JSON string from a javascript object

// a variable
var humanObject = {  
     name : "Nicolas",
     sex : "Unknown"        
}
// we call the function  
console.log(JSON.stringify(humanObject)); 

Set to JSON

How to transform a set to an array

let stringify = JSON.stringify(
            this.root,
            (key, value) => {
                if (typeof value === 'object' && value instanceof Set) {
                    if (value.size > 0) {
                        return [...value];
                    } else {
                        // Don't include children if there is no value
                        return undefined;
                    }
                }
                return value;
            },
            ' '
        );

Exclude from JSON

By returning undefined from the replacer, you exclude any key of the JSON string.

let stringify = JSON.stringify(
            object,
            (key, value) => {
                if (value instanceof Crawler) {
                    return undefined;
                }
                return value;
            },
            null,
            ' '
        );