fast_broken_json_parser

brokenJsonParser.ts

export class BrokenJSONParser {
    static forceParseNested(input: string) {
        if (!input) return null;
        let stringToParse = input;
        try {
            const parsed = JSON.parse(stringToParse);
            return parsed;
        } catch (e) {
            const errorSearchString = 'at position ';
            const startIndex = e.message.indexOf(errorSearchString);

            if (!startIndex || startIndex === -1) {
                return null;
            }

            let errorPosition = e.message.slice(startIndex + errorSearchString.length, e.message.length);
            errorPosition = !isNaN(+errorPosition) ? +errorPosition : null;
            
            if (!errorPosition) { return null; }

            if (stringToParse[errorPosition] === '"') {
                stringToParse = this.setCharAt(stringToParse, (errorPosition), '');
                return this.forceParseNested(stringToParse);
            }

            if (stringToParse[errorPosition - 1] === '"' && stringToParse[errorPosition - 2] === "{") {
                stringToParse = this.setCharAt(stringToParse, (errorPosition - 3), '');
                return this.forceParseNested(stringToParse);
            }

            return null;
        }
    }

    private static setCharAt(str, index, chr) {
        if (index > str.length - 1) return str;
        return str.substring(0, index) + chr + str.substring(index + 1);
    }
}