我知道这个问题已经完成，但我还是不明白。我已经阅读了StackOverFlow自己的"this" keyword解释（以及其中的Mike West文章）以及其他与范围相关的问题。我不知道为什么我没有得到它，所以我期待更精明的JavaScript开发人员寻求帮助。
从代码和评论中，它应该是相当自我解释的。但它正在查询ESRI地图服务，返回图形并将其放置在地图上。
但问题出在showResults函数中，我称之为this.graphics，这是地图的图形属性（图形图层）。我知道它现在超出了范围（花了更多的时间来弄清楚比我想承认的），但我怎么能把它放回范围以便我可以使用它？即使我已经大大改变了代码......
define([
"dojo/_base/declare",
"dojo/on",
"dijit/_WidgetBase",
"dijit/_TemplatedMixin",
"dijit/_WidgetsInTemplateMixin",
"dijit/form/Button",
"dijit/form/Form",
"dijit/form/FilteringSelect",
"dijit/form/ValidationTextBox",
"dojo/_base/array",
"dojo/_base/Color",
"dojo/_base/lang",
"esri/tasks/find",
"dojo/text!./Find/templates/Find.html"
], function(declare, on, _WidgetBase, _TemplatedMixin, _WidgetsInTemplateMixin, Button, Form, FilteringSelect, ValidationTextBox, array, Color, lang, find, FindTemplate) {
//anonymous function to load CSS files required for this module
(function() {
var css = [require.toUrl("gis/dijit/Find/css/Find.css")];
var head = document.getElementsByTagName("head").item(0),
link;
for(var i = 0, il = css.length; i < il; i++) {
link = document.createElement("link");
link.type = "text/css";
link.rel = "stylesheet";
link.href = css[i].toString();
head.appendChild(link);
}
}());
// Query Dijit
return declare([_WidgetBase, _TemplatedMixin, _WidgetsInTemplateMixin], {
widgetsInTemplate: true,
templateString: FindTemplate,
graphics: null,
findTask: null,
findParams: null,
results: [],
serverError: null,
queryLayer: null,
searchText: null,
postCreate: function() {
// Method is used to call a superclass method. It's good practice to assume that you are overriding a method that may
// do something important in a class up the inheritance chain
this.inherited(arguments);
// Create graphics layer and add it to the map
this.graphics = new esri.layers.GraphicsLayer({id:"queryGraphics"});
this.map.addLayer(this.graphics);
// Create find task with url to map service
this.findTask = new esri.tasks.FindTask("arcgis/rest/services/MapServer");
// Create find parameters and define known values
this.findParams = new esri.tasks.FindParameters();
this.findParams.outSpatialReference = this.map.spatialReference;
this.findParams.returnGeometry = true;
this.findParams.layerIds = [1];
this.findParams.searchFields = ["OBJECTID", "Gauge ID", "FV_ID", "FDC_ID", "Flood_Stage", "Flood_Line", "Municipality", "WATERSHED"];
// Listen for Submit button click
on(this.submitButton, 'click', lang.hitch(this, 'execute'));
},
// Submit button click event
execute: function execute() {
// Set the WHERE search text
this.findParams.searchText = dojo.byId("searchText").value;
// Sends a request to the ArcGIS REST map service resource to perform a search based
// on the FindParameters specified in the findParameters argument. On completion, the
// onComplete event is fired and the optional callback function is invoked.
this.findTask.execute(this.findParams, this.showResults, this.showError);
},
// Fires when the find operation is complete and returns an array of FindResult
showResults: function showResults(results) {
this.graphics.clear();
// Build an array of attribute information and add each found graphic to the map
dojo.forEach(results, function(result) {
var symbol;
switch(result.feature.geometry.type) {
case "point":
symbol = new esri.symbol.SimpleMarkerSymbol(esri.symbol.SimpleMarkerSymbol.STYLE_CIRCLE, 10, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID, new Color([255, 0, 0]), 1), new Color([255, 0, 0, 1.0]));
break;
case "polyline":
symbol = new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_DASH, new Color([255, 0, 0]), 1);
break;
case "polygon":
symbol = new esri.symbol.SimpleFillSymbol(esri.symbol.SimpleFillSymbol.STYLE_SOLID, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_DASHDOT, new Color([255, 0, 0]), 2), new Color([255, 255, 0, 0.0]));
break;
default:
symbol = new esri.symbol.SimpleMarkerSymbol(esri.symbol.SimpleMarkerSymbol.STYLE_CIRCLE, 10, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID, new Color([255, 0, 0]), 1), new Color([255, 0, 0, 1.0]));
}
var graphic = new esri.Graphic(result.feature.geometry, symbol);
this.graphics.add(graphic);
});
},
// Fires if the find execution fails to complete
showError: function showError(serverError) {
alert("The server encountered an error. Error: " + serverError);
}
});
});
答复后更新：
所以，解决这个问题不是一个答案，而是两个问题的结合。我收录了Buffalo的回答
this.findTask.execute(this.findParams, lang.hitch(this, this.showResults), this.showError);
和Buffalo对Craig的答案的评论
dojo.forEach(results, function(result) {
...
}, this);
所以我将布法罗的标记作为答案，但这三个都值得为更多读者寻找。
答案 0 :(得分：1)
您可以使用 Function.bind （请注意！所有浏览器都不支持此功能。）
变化：
this.findTask.execute(this.findParams, this.showResults, this.showError);
要：
this.findTask.execute(this.findParams, this.showResults.bind(this), this.showError);
或（如果您担心Function.bind浏览器支持）：
使用closure＆amp; Function.apply
execute: function execute() {
...
...
var self = this;
this.findTask.execute(this.findParams, function() {
self.showResults.apply(self, arguments);
}, this.showError);
}
答案 1 :(得分：1)
hitch中的dojo/_base/lang方法将成为您最好的朋友。我假设findTask函数执行的操作是异常一些异步请求，然后使用结果调用第二个参数。
首先，将dojo/_base/lang添加到您的依赖关系列表中。
然后，更改行
this.findTask.execute(this.findParams, this.showResults, this.showError);
到
this.findTask.execute(this.findParams, lang.hitch(this,this.showResults), this.showError);
lang#hitch做的是获取第一个参数（在本例中是小部件的实例），并使其成为第二个参数执行时的范围。在这种情况下，我们希望showResults在当前范围内执行。
答案 2 :(得分：1)
您的问题是以下代码
dojo.forEach(results, function(result) {
...
this.graphics.add(graphic);
});
正在执行的函数没有小部件的范围。成功：
dojo.forEach(results, lang.hitch(this, function(result) {
}));