solid1.md

开放/关闭原则(OCP)

Bad

	class AjaxAdapter extends Adapter {
	  constructor() {
	    super();
	    this.name = "ajaxAdapter";
	  }
	}
	
	class NodeAdapter extends Adapter {
	  constructor() {
	    super();
	    this.name = "nodeAdapter";
	  }
	}
	
	class HttpRequester {
	  constructor(adapter) {
	    this.adapter = adapter;
	  }
	
	  fetch(url) {
	    if (this.adapter.name === "ajaxAdapter") {
	      return makeAjaxCall(url).then(response => {
	        // transform response and return
	      });
	    } else if (this.adapter.name === "nodeAdapter") {
	      return makeHttpCall(url).then(response => {
	        // transform response and return
	      });
	    }
	  }
	}
	
	function makeAjaxCall(url) {
	  // request and return promise
	}
	
	function makeHttpCall(url) {
	  // request and return promise
	}

Good

	class AjaxAdapter extends Adapter {
	  constructor() {
	    super();
	    this.name = "ajaxAdapter";
	  }
	
	  request(url) {
	    // request and return promise
	  }
	}
	
	class NodeAdapter extends Adapter {
	  constructor() {
	    super();
	    this.name = "nodeAdapter";
	  }
	
	  request(url) {
	    // request and return promise
	  }
	}
	
	class HttpRequester {
	  constructor(adapter) {
	    this.adapter = adapter;
	  }
	
	  fetch(url) {
	    return this.adapter.request(url).then(response => {
	      // transform response and return
	    });
	  }
	}