IE does not support getElementsByClassName The final perfect solution_Basic knowledge

The current solution is to determine whether the browser supports this method. If it supports it, leave it alone. If it does not support it, add the getElementsByClassName method to the document object. This way of writing has the advantage that you don’t have to go there regardless of whether there is a native function or not. Modify the code.

Usually use getElementsByTagName("*") to retrieve all elements in the document, then traverse, use regular expressions to find matching elements, put them into an array and return them. Since IE5 does not support document.getElementsByTagName("*"), use the branch document.all to prevent errors

The following method perfectly supports document writing

Copy code The code is as follows:

if (!document.getElementsByClassName){
document.getElementsByClassName = function(className, element){
var children = (element || document).getElementsByTagName('*');
var elements = new Array( );
for (var i=0; ivar child = children[i];
var classNames = child.className.split(' ');
for (var j=0; jif (classNames[j] == className){
elements.push(child);
break;
}
}
}
return elements;
};
}

The final solution is:

Copy code The code is as follows:

var getElementsByClassName = function (searchClass, node,tag) {
if(document.getElementsByClassName){
var nodes = (node ​​|| document).getElementsByClassName(searchClass),result = [];
for(var i=0 ;node = nodes[i ];){
if(tag !== "* " && node.tagName === tag.toUpperCase()){
result.push(node)
}else{
result.push(node)
}
}
return result
}else{
node = node || document;
tag = tag || "*";
var classes = searchClass.split(" "),
elements = ( tag === "*" && node.all)? node.all : node.getElementsByTagName(tag),
patterns = [],
current,
match;
var i = classes. length;
while(--i >= 0){
patterns.push(new RegExp("(^|s)" classes[i] "(s|$)"));
}
var j = elements.length;
while(--j >= 0){
current = elements[j];
match = false;
for(var k= 0, kl=patterns.length; kmatch = patterns[k].test(current.className);
if (!match) break;
}
if (match) result.push(current);
}
return result;
}
}