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dojo/io-query源码解析

该模块主要对url中的query部分进行处理，我们发送GET请求时，将参数直接放在URL中，经常碰到的需求就是把一个对象转化为query字符串放到url中去发送GET请求。io-query模块便提供了两个方法来处理query：

objectToQuery将一个object转化成query字符串
queryToObject将query字符串转化成对象

从对象转化成query是拼接的过程，对象的字段和值都需要编码

objectToQuery: function objectToQuery(/*Object*/ map){  // summary:  //  takes a name/value mapping object and returns a string representing  //  a URL-encoded version of that object.  // example:  //  this object:  //  // | {  // |  blah: "blah",  // |  multi: [  // |   "thud",  // |   "thonk"  // |  ]  // | };  //  //  yields the following query string:  //  // | "blah=blah&multi=thud&multi=thonk"  var enc = encodeURIComponent, pairs = [];  for(var name in map){   var value = map[name];   // backstop是一个空对象，目的是防止像toString这种继承来的字段被处理   if(value != backstop[name]){    var assign = enc(name) + "=";    if(lang.isArray(value)){     //数组的话对每一个数组元素都编码成：multi=thud&multi=thonk     for(var i = 0, l = value.length; i < l; ++i){      pairs.push(assign + enc(value[i]));     }    }else{     pairs.push(assign + enc(value));    }   }  }  return pairs.join("&"); // String }

query到对象是字符串分割的过程，参数和参数值都需要使用decodeURIComponent来解码

queryToObject: function queryToObject(/*String*/ str){  // summary:  //  Create an object representing a de-serialized query section of a  //  URL. Query keys with multiple values are returned in an array.  //  // example:  //  This string:  //  // |  "foo=bar&foo=baz&thinger=%20spaces%20=blah&zonk=blarg&"  //  //  results in this object structure:  //  // |  {  // |   foo: [ "bar", "baz" ],  // |   thinger: " spaces =blah",  // |   zonk: "blarg"  // |  }  //  //  Note that spaces and other urlencoded entities are correctly  //  handled.  // 字符串分割  var dec = decodeURIComponent, qp = str.split("&"), ret = {}, name, val;  for(var i = 0, l = qp.length, item; i < l; ++i){   item = qp[i];   if(item.length){    var s = item.indexOf("=");    if(s < 0){// 空值     name = dec(item);     val = "";    }else{     // 分割"a=b"的形式，name为a，val为b     name = dec(item.slice(0, s));     val  = dec(item.slice(s + 1));    }    //一个name对应多个value则转化为数组    if(typeof ret[name] == "string"){ // inline'd type check     ret[name] = [ret[name]];    }    if(lang.isArray(ret[name])){     ret[name].push(val);    }else{     ret[name] = val;    }   }  }  return ret; // Object }

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