export function bufFromString(str: string): Buffer {
  const length = Buffer.byteLength(str);
  const buffer = Buffer.allocUnsafe
    ? Buffer.allocUnsafe(length)
    : new Buffer(length);
  buffer.write(str);
  return buffer;
}

export function emptyBuffer(): Buffer{
  const buffer = Buffer.allocUnsafe
    ? Buffer.allocUnsafe(0)
    : new Buffer(0);
  return buffer;
}

export function filterArray(arr: any[], filter: number[]): any[] {
  const rtn: any[] = [];
  for (let i = 0; i < arr.length; i++) {
    if (filter.indexOf(i) > -1) {
      rtn.push(arr[i]);
    }
  }
  return rtn;
}

export const trimLeft=String.prototype.trimLeft?function trimLeftNative(str:string){
  return str.trimLeft();
}:function trimLeftRegExp(str:string){
  return str.replace(/^\s+/, "");
}

export const trimRight=String.prototype.trimRight?function trimRightNative(str:string){
  return str.trimRight();
}:function trimRightRegExp(str:string){
  return str.replace(/\s+$/, "");
}