Builder pattern in JavaScript

client.js

function executeWithFetch(request) {
  // EXERCISE FOR THE READER
}

function executeWithAxios(request) {
  // EXERCISE FOR THE READER
}

function ClientBuilder() {
  return {
    forBaseUrl: function(baseUrl) {
      this.baseUrl = baseUrl;
      return this;
    }
    
    withHeaders: function(headers) {
      this.headers = headers;
      return this;
    }
    
    usingFetch: function() {
      this.executor = executeWithFetch;
      return this;
    }
  
    usingAxios: function() {
      this.executor = executeWithAxios;
      return this;
    }
  
    build: function() {
      return new Client(this.baseUrl, this.headers, this.executor);
    }
  }
}

function Client(baseUrl, headers, executor) {
  this.baseUrl = baseUrl;
  this.headers = headers;
  this.executor = executor;
  
  this.post = function(endpoint, data) {
    const url = `${this.baseUrl}${endpoint}`;
    return this.executor({
      url,
      data,
      method: 'POST',
      headers: this.headers
    });
  }

  this.get = function(endpoint, params) {
    const url = `${this.baseUrl}${endpoint}`;
    return this.executor({
      url,
      params,
      method: 'GET',
      headers: this.headers
    });
  }
}

In L43 and L53 you forgot to close the template string

Thank you!