A cssQuery object javascript script implementation code_js object-oriented

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/**
* @author Supersha
* @QQ:770104121
*/
var cssQuery = {
//parent: used to store a reference to the parent node of the current node
parent: document,
select: function(selectorStr){
var selectors=selectorStr.split(" "); // Separated string
for (var i = 0, len = selectors.length; i < len; i ) {
var el = this.parent || document; //Node used to store specified class attributes Reference
var val=this.replaceStr(selectors[i]); //Replace the "#" and "." dots to obtain the node reference of the specified ID
if (selectors.length == 1) { //If there is only one parameter
if (!(/[#.]/g).test(selectors[i])) { //If it is an HTML tag
return document.getElementsByTagName(selectors[ i]);
}
else { //If it is an ID or a specified class value
//Determine whether it is an ID or a class attribute
return (this.IDLabel(selectors[i]))? this.$(val) : this.getElementsByClassName(document, "*", val);
}
}
//If the last ID or class or HTML tag in the selectorStr character is reached
else if(i == selectors.length-1){
if (!(/[#.]/g).test(selectors[i])) { //If it is an HTML tag
return el .getElementsByTagName(selectors[i]);
}
else { //If it is an ID or class attribute
return (this.IDLabel(selectors[i])) ? this.$(val) : this .getElementsByClassName(el,"*",val);
}
}
else{ //If there are more than two levels of selectorStr, store the reference of the current node in the parent attribute
if ( !(/[#.]/g).test(selectors[i])) { //If it is an HTML tag
this.parent = el.getElementsByTagName(selectors[i])[0];
}
else { //If it is an ID or class attribute
this.parent = ((/#/gi).test(selectors[i])) ? this.$(val) : el;
}
}
}
},
$: function(id){ //Reference used to get the specified ID
return document.getElementById(id);
},
IDLabel: function(selector){ //Determine whether it is an ID attribute
return ((/#/gi).test(selector)) ? true : false;
},
classLabel: function(selector ){ //Determine whether it is a class attribute
return ((/./gi).test(selector)) ? true : false;
},
replaceStr:function(a){ //Replace "#" and "." dots are used to obtain the node reference of the specified ID
return a.replace("#","").replace(".","");
},
getElementsByClassName: function(el, tag, classname){ //Get the reference of the element containing the class attribute value through the class attribute value
var elem = el || document;
if (!classname)
return;
tag = tag || "*";
var allTagsDom = ((tag == "*") && (elem.all)) ? elem.all : elem.getElementsByTagName(tag);
classname = classname.replace(/-/g, "\-");
var regex = new RegExp("(^|\s*)" classname "(\s*|$)");
var matchElements = new Array();
var element;
for (var i = 0; i < allTagsDom.length; i ) {
element = allTagsDom[i];
if (regex.test(element.className)) { //Detect class names according to regular rules
matchElements.push(element);
}
}
return matchElements;
}
}
//Call method: cssQuery.select(selectorString); selectorString like this: "#p #b .em",
//Can receive a combination of HTML tags, ID, and class, and return the specified selectorString References