typescriptでの入力バリデーション

validation.ts

export class validation {
  private errorMsg = {
    'require': "入力が空です",
    'min_length': "{$target}文字以上で入力して下さい",
    'max_length': "{$target}文字以下で入力して下さい"
  };

  public msg:any;

  constructor(){
    this.msg = [];
  }

  public require(input:string): void{
    if (input === ""){
      this.msg.push(this.error_message());
    }
  }

  public min_length(input:string, param:{min:number}): void{
    if (input.length < param.min){
      var msg = this.error_message();
      msg = this.msg_replace(msg, param.min);
      this.msg.push(msg);
    }
  }

  public max_length(input:string, param:{max:number}): void{
    if (input.length > param.max){
      var msg = this.error_message();
      msg = this.msg_replace(msg, param.max);
      this.msg.push(msg);
    }
  }
  
  private error_message(): string{
    var call_name = this.error_message.caller.name;

    var msg:string = "";
    if (call_name==="require"){
      msg = this.errorMsg.require;
    }else if(call_name==="min_length"){
      msg = this.errorMsg.min_length;
    }else if(call_name==="max_length"){
      msg = this.errorMsg.max_length;
    }
    
    return msg;
  }

  private msg_replace(msg:string, replace:any): string{
    return msg.replace(/$target/g, replace);
  }
}

export class observer{
  private listeners:any;
  private errorMsg:any;

  public on(func:any, param:any): void {
    this.listeners.push({func: func, param: param});
  }

  public trigger(input:string): void {
    for(var i=0; i<this.listeners.length; i++){
      if (typeof this.listeners[i] === "function") this.listeners[i]['func'](input, this.listeners[i]['param']);
    }
    this.listeners = [];

    return this.errorMsg;
  }
}

const valid = new validation();
const input:string = "";

const obsrv = new observer();
obsrv.on(valid.require, {input:input});
obsrv.on(valid.min_length, {input:input, min:2});
obsrv.on(valid.max_length, {input:input, max:10});

console.log(valid.msg);