TextInserter. (javascript)

TextInserter.js

class TextInserter{
  constructor(selector, text){
    this.selector=selector
    this.text=text;
    this.field=$(selector).get(0);
    this.value=$(selector).val();
    this.start=this.field.selectionStart;
    this.finish=this.field.selectionEnd;

    this.putText();
  }

  putText(){
    this.value=this.value.substr(0, this.start) + this.text + this.value.substr(this.finish);
    $(this.selector).val(this.value);
  }
}//TextInserter

var obj=new TextInserter('textarea', 'some text');