find: function ( selector ) {
// 当表达式不包含“,”符号时候
if ( this .length === 1 && !/,/.test(selector) ) {
var ret = this .pushStack( [], "find" , selector );
ret.length = 0;
jQuery.find( selector, this [0], ret );
return ret;
}
// 当表达式包含“,”符号时候
else {
var elems = jQuery.map( this , function (elem){
return jQuery.find( selector, elem );
});
return this .pushStack( /[^+>] [^+>]/.test( selector ) ?
jQuery.unique( elems ) :
elems, "find" , selector );
}
}
//其中的jQuery.find是这样一个方法：
jQuery.find = Sizzle.find;
//而sizzle又是这样一个方法：
var Sizzle = function (selector, context, results, seed) {
results = results || [];
context = context || document;
if ( context.nodeType !== 1 && context.nodeType !== 9 )
return [];
if ( !selector || typeof selector !== "string" ) {
return results;
}
var parts = [], m, set, checkSet, check, mode, extra, prune = true ;
// Reset the position of the chunker regexp (start from head)
chunker.lastIndex = 0;
while ( (m = chunker.exec(selector)) !== null ) {
parts.push( m[1] );
if ( m[2] ) {
extra = RegExp.rightContext;
break ;
}
}
if ( parts.length > 1 && origPOS.exec( selector ) ) {
if ( parts.length === 2 && Expr.relative[ parts[0] ] ) {
set = posProcess( parts[0] + parts[1], context );
} else {
set = Expr.relative[ parts[0] ] ?
[ context ] :
Sizzle( parts.shift(), context );
while ( parts.length ) {
selector = parts.shift();
if ( Expr.relative[ selector ] )
selector += parts.shift();
set = posProcess( selector, set );
}
}
} else {
var ret = seed ?
{ expr: parts.pop(), set: makeArray(seed) } :
Sizzle.find( parts.pop(), parts.length === 1 && context.parentNode ? context.parentNode : context, isXML(context) );
set = Sizzle.filter( ret.expr, ret.set );
if ( parts.length > 0 ) {
checkSet = makeArray(set);
} else {
prune = false ;
}
while ( parts.length ) {
var cur = parts.pop(), pop = cur;
if ( !Expr.relative[ cur ] ) {
cur = "" ;
} else {
pop = parts.pop();
}
if ( pop == null ) {
pop = context;
}
Expr.relative[ cur ]( checkSet, pop, isXML(context) );
}
}
if ( !checkSet ) {
checkSet = set;
}
if ( !checkSet ) {
throw "Syntax error, unrecognized expression: " + (cur || selector);
}
if ( toString.call(checkSet) === "[object Array]" ) {
if ( !prune ) {
results.push.apply( results, checkSet );
} else if ( context.nodeType === 1 ) {
for ( var i = 0; checkSet[i] != null ; i++ ) {
if ( checkSet[i] && (checkSet[i] === true || checkSet[i].nodeType === 1 && contains(context, checkSet[i])) ) {
results.push( set[i] );
}
}
} else {
for ( var i = 0; checkSet[i] != null ; i++ ) {
if ( checkSet[i] && checkSet[i].nodeType === 1 ) {
results.push( set[i] );
}
}
}
} else {
makeArray( checkSet, results );
}
if ( extra ) {
Sizzle( extra, context, results, seed );
}
return results;
};
