MasatoraSakikoyama

{
    "presets": [
        ["env", {
            "modules": false,
            "targets": {
                "browsers": [
                    "last 2 versions",
                    "Explorer >= 8"
                ]
            }

MasatoraSakikoyama

Array.prototype.sum = function() {
  return this.reduce((prev, curr) => prev + curr);
}

MasatoraSakikoyama

Array.range = function(start, end, step) {
    if (end || isNaN(end)) {
        end = start || 0;
        start = 0;
    }
    if (step || isNaN(step)) {
        step = start < end ? 1 : -1;
    }

    const length = Math.max(Math.ceil((end - start) / step), 0) || 0;

MasatoraSakikoyama

Array.range = function*(start, end, step) {
    if (end || isNaN(end)) {      
        end = start || 0;  
        start = 0;
    }
    if (step || isNaN(step)) {
        step = start < end ? 1 : -1;    
    }
 
    const length = Math.max(Math.ceil((end - start) / step), 0) || 0;