jQueryで実装しているXML,JSON parserを覗いてみる

parseJSON: function( data ) {
    if ( typeof data !== "string" || !data ) {
        return null;
    }

    // Make sure leading/trailing whitespace is removed (IE can't handle it)
    data = jQuery.trim( data );

    // Attempt to parse using the native JSON parser first
    if ( window.JSON && window.JSON.parse ) {
        return window.JSON.parse( data );
    }

    // Make sure the incoming data is actual JSON
    // Logic borrowed from http://json.org/json2.js
    if ( rvalidchars.test( data.replace( rvalidescape, "@" )
        .replace( rvalidtokens, "]" )
        .replace( rvalidbraces, "")) ) {

        return ( new Function( "return " + data ) )();

    }
    jQuery.error( "Invalid JSON: " + data );
},

// Cross-browser xml parsing
parseXML: function( data ) {
    if ( typeof data !== "string" || !data ) {
        return null;
    }
    var xml, tmp;
    try {
        if ( window.DOMParser ) { // Standard
            tmp = new DOMParser();
            xml = tmp.parseFromString( data , "text/xml" );
        } else { // IE
            xml = new ActiveXObject( "Microsoft.XMLDOM" );
            xml.async = "false";
            xml.loadXML( data );
        }
    } catch( e ) {
        xml = undefined;
    }
    if ( !xml || !xml.documentElement || xml.getElementsByTagName( "parsererror" ).length ) {
        jQuery.error( "Invalid XML: " + data );
    }
    return xml;
},