non-overlapping-intervals.js

/**
 * @param {number[][]} intervals
 * @return {number}
 */

var eraseOverlapIntervals = function(intervals) {
 
    // corner case
    
    if (intervals.length === 0) {
         return 0;
     }
 
     // normal case
     
    intervals = intervals.sort((a, b) => a[1] - b[1]);
     
    let end = intervals[0][1];
    let count = 1;
    
    for (let i = 1; i < intervals.length; i++) {
         
    if (intervals[i][0] >= end) {
             end = intervals[i][1];
             count++;
         }
     }
    
     return intervals.length - count;
    
};