iteration JSON object

// My example
rows.forEach(element => {
            let json = JSON.parse(element.template_source);
            for (let key in json) {
                if(key === 'details') {
                    json[key].forEach(element => {
                        if(element.level !== undefined) {
                            console.log(element.level);
                        }
                    })
                }
            }
        });

        // ES6
        rows.forEach(element => {
            let json = JSON.parse(element.template_source);
            for (const key of Object.keys(json)) {
                if(key === "details") {
                    json[key].forEach(details => {
                        console.log(details.level);
                    })
                }
            }
        });

        // ES7
        rows.forEach(element => {
            let json = JSON.parse(element.template_source);
            Object.entries(json).forEach(
                ([key, value]) => {
                    if (key === "details") {
                        json[key].forEach(details => {
                            console.log(details.level);
                        })
                    }
                }
            )
        })