export const sleep = (milliseconds) => new Promise(resolve => setTimeout(resolve, milliseconds));

Array.range = function(n) {
    return Array.from(Array(n), (v, k) => k);
 }

前後の空白をそのままに行ごとにmapする

String.prototype.mapLine = function(func) { 
    return (this.split(/\n/).map(line => [line.match(/^\s*/), func(line.trim()), line.match(/\s*$/)].join("")).join('\n'));
}

String.prototype.sandwich = function(left,right) { 
  return (this. replace(/(.+)/g, left+"$1"+right));
}

String.prototype.mathEsc = function() { 
    return (this.replace(/\s/g,"\\ "). replace(/\^/,"\^\\wedge"));
}

String.prototype.mathMode = function() { 
  return (this.sandwich("[\$ "," ]"));
}