[рони]

valya2021,

<pre>
    <script>
        const data = [{
                x1: 1,
                x2: 4,
                order: 0
            },
            {
                x1: 7,
                x2: 10,
                order: 0
            },
            {
                x1: 5,
                x2: 8,
                order: 0
            },
            {
                x1: 10,
                x2: 13,
                order: 0
            },
            {
                x1: 8,
                x2: 11,
                order: 0
            },
            {
                x1: 8,
                x2: 11,
                order: 0
            }
        ];


        let arr = Object.keys(data);
        let order = 1;
        while (arr.length) {
            let min = data[arr[0]].x1;
            for (let i = 0; i < arr.length;) {
                let k = arr[i];
                let {
                    x1,
                    x2
                } = data[k];
                if (x1 >= min) {
                    data[k].order = order;
                    min = x2;
                    arr.splice(i, 1);
                } else i++
            }
            order++;
        }

        document.write(JSON.stringify(data, "", 1))
    </script></pre>