javascript

CHAPTER 10 ■ SCRIPTING BOM
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{
"href": "ten.html",
"src": "images/vomero.jpg",
"alt": "Nike Zoom Vomero"
},
{
"href": "ten.html",
"src": "images/max.jpg",
"alt": "Nike Air Max"
}
]);
Let’s define a function named parseJSONP. Insofar as we’re not making an parseJSONP request, let’s
name the parameter data, not req. As we’ve done several times before, move prep() from parseJSON() to
parseJSONP(). However, rather than call getData() for data/s6.js, simply call parseJSONP() instead.
Remember, we’re bypassing XMLHttpRequest entirely.
function parseJSON(req) {
if (req.status === 200 || req.status === 304) {
var data = JSON.parse(req.responseText);
var div, ul = createElem("ul", {className: "slide"}), li;
for (var i = 0, j = data.length; i < j; i ++) {
li = createElem("li", null, [
createElem("a", {href: data[i].href}, [
createElem("img", {src: data[i].src, alt: data[i].alt})])]);
ul.appendChild(li);
}
div = createElem("div", {className: "scroller", id: "s5"}, [
createElem("div", {className: "wrapper"}, [ul]),
createElem("div", {className: "left arrow sprite"}),
createElem("div", {className: "right arrow sprite"})]);
document.body.appendChild(div);
}
parseJSONP();
}
function parseJSONP(data) {
prep();
}
Now when parseJSON() calls parseJSONP(), data will be undefined. In that event, we want to define
padJSON(), the JSON-P callback function. But it has to be global so that it is callable from data/s6.js.
Remember, none of the functions in ten.js is global. They’re all saved to the call object of the selfinvoking
function wrapping the script.
So by way of a closure, we’ll make parseJSONP() callable from the global scope like so. Remember
from Chapter 6 that arguments.callee refers to the function that is runningparseJSONP().
function parseJSONP(data) {
if (typeof data === "undefined") {
var f = arguments.callee;
window.padJSON = function(d) {
f(d);
};