问题
I'm developing a widget that creates basic SEO tags that could already exist on a page so I'm wanting to make sure the widget checks for existing tags before the new tag is generated.
For example, one of the tags that the widget produces is
<meta name="description" content="Description of the webpage"/>
Since this tag is one that most pages already have, is there a way to use javascript to check for the tag before writing it?
回答1:
Here is the plain Javascript solution (no libraries):
Check for the meta description element using:
document.querySelector("meta[name=description]");
If found, access its content attribute using .getAttribute("content").
Demo:
if(document.querySelector("meta[name=description]")){
if(document.querySelector("meta[name=description]").getAttribute("content") === "Description of the webpage")
console.log("meta description with content 'Description of the webpage' found");
// do something
}
else{
console.log("meta description not found");
// do something
}<meta name="description" content="Description of the webpage"/>Read up:
- How to check if element exists in the visible DOM?
- How do I get the information from a meta tag with javascript?
Source
回答2:
Sure its possible. Just use something like:
var description = $('meta[name=description]').attr("content");
Check the fiddle: https://jsfiddle.net/034ghy1y/
回答3:
This will return the first meta tag found on a page.
var tag = document.getElementsByTagName("meta")
if(tag[0]) {
console.log('found ' + tag[0]);
} else {
console.log("Not found")
}
http://plnkr.co/edit/Gj9x5l8yS9xh2BoWkAm8?p=preview
来源：https://stackoverflow.com/questions/29647336/how-to-check-for-existing-meta-tag-before-generating-a-new-one-with-javascript