javascript跨域on-demand访问web service

一片重要的文章，《JSON and the Dynamic Script Tag: Easy, XML-less Web Services for JavaScript》
地址：


附录：

（注：webservice要生成合适的javascript代码返回，并调用回调函数）

// A SECURITY WARNING FROM DOUGLAS CROCKFORD:

// "The dynamic

//

// function callbackfunc(jsonData) {

// alert('Latitude = ' + jsonData.ResultSet.Result[0].Latitude +

// ' Longitude = ' + jsonData.ResultSet.Result[0].Longitude);

// aObj.removeScriptTag();

// }

//

// request = '

// output=json&callback=callbackfunc&location=78704';

// aObj = new JSONscriptRequest(request);

// aObj.buildScriptTag();

// aObj.addScriptTag();

//

//



// Constructor -- pass a REST request URL to the constructor

//

function JSONscriptRequest(fullUrl) {
    // REST request path

    this.fullUrl = fullUrl;
    // Keep IE from caching requests

    this.noCacheIE = '&noCacheIE=' + (new Date()).getTime();
    // Get the DOM location to put the script tag

    this.headLoc = document.getElementsByTagName("head").item(0);
    // Generate a unique script tag id

    this.scriptId = 'JscriptId' + JSONscriptRequest.scriptCounter++;
}

// Static script ID counter

JSONscriptRequest.scriptCounter = 1;

// buildScriptTag method

//

JSONscriptRequest.prototype.buildScriptTag = function () {

    // Create the script tag

    this.scriptObj = document.createElement("script");
    
    // Add script object attributes

    this.scriptObj.setAttribute("type", "text/javascript");
    this.scriptObj.setAttribute("charset", "utf-8");
    this.scriptObj.setAttribute("src", this.fullUrl + this.noCacheIE);
    this.scriptObj.setAttribute("id", this.scriptId);
}
 
// removeScriptTag method

//

JSONscriptRequest.prototype.removeScriptTag = function () {
    // Destroy the script tag

    this.headLoc.removeChild(this.scriptObj);
}

// addScriptTag method

//

JSONscriptRequest.prototype.addScriptTag = function () {
    // Create the script tag

    this.headLoc.appendChild(this.scriptObj);
}


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