docs(async): edit promise

ruanyf · ruanyf · commit e993d171d2af · 2018-02-23T12:50:40.000+08:00
diff --git a/docs/async/promise.md b/docs/async/promise.md
@@ -202,11 +202,9 @@ f1().then(f2)
   .then(f3);
 ```
 
-## Promise &#30340;&#23454;&#20363;
+## &#23454;&#20363;&#65306;&#22270;&#29255;&#21152;&#36733;
 
-### &#21152;&#36733;&#22270;&#29255;
-
-&#25105;&#20204;&#21487;&#20197;&#25226;&#22270;&#29255;&#30340;&#21152;&#36733;&#20889;&#25104;&#19968;&#20010;`Promise`&#23545;&#35937;&#12290;
+&#19979;&#38754;&#26159;&#20351;&#29992; Promise &#23436;&#25104;&#22270;&#29255;&#30340;&#21152;&#36733;&#12290;
 
 ```javascript
 var preloadImage = function (path) {
@@ -219,83 +217,12 @@ var preloadImage = function (path) {
 };
 ```
 
-### Ajax &#25805;&#20316;
-
-Ajax &#25805;&#20316;&#26159;&#20856;&#22411;&#30340;&#24322;&#27493;&#25805;&#20316;&#65292;&#20256;&#32479;&#19978;&#24448;&#24448;&#20889;&#25104;&#19979;&#38754;&#36825;&#26679;&#12290;
-
-```javascript
-function search(term, onload, onerror) {
-  var xhr, results, url;
-  url = 'http://example.com/search?q=' + term;
-
-  xhr = new XMLHttpRequest();
-  xhr.open('GET', url, true);
-
-  xhr.onload = function (e) {
-    if (this.status === 200) {
-      results = JSON.parse(this.responseText);
-      onload(results);
-    }
-  };
-  xhr.onerror = function (e) {
-    onerror(e);
-  };
-
-  xhr.send();
-}
-
-search('Hello World', console.log, console.error);
-```
-
-&#22914;&#26524;&#20351;&#29992; Promise &#23545;&#35937;&#65292;&#23601;&#21487;&#20197;&#20889;&#25104;&#19979;&#38754;&#36825;&#26679;&#12290;
+&#19978;&#38754;&#30340;`preloadImage`&#20989;&#25968;&#29992;&#27861;&#22914;&#19979;&#12290;
 
 ```javascript
-function search(term) {
-  var url = 'http://example.com/search?q=' + term;
-  var xhr = new XMLHttpRequest();
-  var result;
-
-  var p = new Promise(function (resolve, reject) {
-    xhr.open('GET', url, true);
-    xhr.onload = function (e) {
-      if (this.status === 200) {
-        result = JSON.parse(this.responseText);
-        resolve(result);
-      }
-    };
-    xhr.onerror = function (e) {
-      reject(e);
-    };
-    xhr.send();
-  });
-
-  return p;
-}
-
-search('Hello World').then(console.log, console.error);
-```
-
-&#21152;&#36733;&#22270;&#29255;&#30340;&#20363;&#23376;&#65292;&#20063;&#21487;&#20197;&#29992; Ajax &#25805;&#20316;&#23436;&#25104;&#12290;
-
-```javascript
-function imgLoad(url) {
-  return new Promise(function (resolve, reject) {
-    var request = new XMLHttpRequest();
-    request.open('GET', url);
-    request.responseType = 'blob';
-    request.onload = function () {
-      if (request.status === 200) {
-        resolve(request.response);
-      } else {
-        reject(new Error('&#22270;&#29255;&#21152;&#36733;&#22833;&#36133;&#65306;' + request.statusText));
-      }
-    };
-    request.onerror = function () {
-      reject(new Error('&#21457;&#29983;&#32593;&#32476;&#38169;&#35823;'));
-    };
-    request.send();
-  });
-}
+preloadImage('https://example.com/my.jpg')
+  .then(function (e) { document.body.append(e.target) })
+  .then(function () { console.log('&#21152;&#36733;&#25104;&#21151;') })
 ```
 
 ## &#23567;&#32467;
