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SEO Keyword summary for developer.mozilla.org/en-us/docs/web/javascript/reference/errors/regex_invalid_named_capture_reference
Keywords are extracted from the main content of your website and are the primary indicator of the words this page could rank for. By frequenty count we expect your focus keyword to be invalid
Focus keyword
Short and long tail
Short Tail Keywords invalid regular not |
long Tail Keywords (2 words) regular expressionsyntaxerror expressionsyntaxerror invalid regular expression missing after named capture |
long Tail Keywords (3 words) regular expressionsyntaxerror invalid x is not reference in regular invalid named capture named capture reference cant be used cannot be used |
developer.mozilla.org On-Page SEO Scan
Descriptive Elements
The <head> element of a developer.mozilla.org/en-us/docs/web/javascript/reference/errors/regex_invalid_named_capture_reference page is used to inform the browser and visitors of the page about the general meta information. The head section of the page is where we place the page title, the definition of the HTML version used, the language of in which the page is written. In the head section we can also include JavaScript and CSS (markup) files for the page.
Page title
Title length
mozilla logo
Meta description
Meta description legth
Meta description SEO
javascript exception invalid named capture reference regular expression occurs pattern contains backreference does not refer group before similar error message thrown sequence encountered but followed
Content SEO
Number of Words
Spam detected?
Headings
Heading distribution
Heading normalisation
Heading SEO impact
Emphasis (bold and italic)
Emphasis SEO impact
Images
Number of images
Mobile SEO developer.mozilla.org/en-us/docs/web/javascript/reference/errors/regex_invalid_named_capture_reference
Mobile rendering
Mobile optimizations
Responsive design detected (mobile css)
No flash detected !
Mobile improvement
Marketing / lead generation for developer.mozilla.org/en-us/docs/web/javascript/reference/errors/regex_invalid_named_capture_reference
Social Media
Facebook shares | Facebook likes | ||
Facebook comments | Tweets | ||
Google +1 |
Conversion form
Search form
Analytics
Online presence
SERP Preview
SERP Title
SERP Link
SERP Description
Domain Level SEO
Domain name
21 characters long
Domain name SEO Impact
Path name
capture found in path !
invalid found in path !
javascript found in path !
name found in path !
named found in path !
reference found in path !
valid found in path !
web found in path !
Structured data
Publisher Markup
Other Structured data
Website configuration
Correct processing of non-existing pages?
Favicon icon found?
Robots.txt found?
Sitemap found?
Navigation and internal links
Navigation
Url seperator
Human readable urls
Number of links
Link SEO Impact
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references
syntaxerror invalid named capture reference in regular expression
javascript basics
javascript first steps
javascript building blocks
introducing javascript objects
introduction
grammar and types
control flow and error handling
loops and iteration
functions
expressions and operators
numbers and dates
text formatting
regular expressions
indexed collections
keyed collections
working with objects
using classes
using promises
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iterators and generators
meta programming
javascript modules
clientside javascript frameworks
clientside web apis
language overview
javascript data structures
equality comparisons and sameness
enumerability and ownership of properties
closures
inheritance and the prototype chain
memory management
concurrency model and event loop
aggregateerror
asyncgenerator
asyncgeneratorfunction
biguint64array
decodeuricomponent
encodeuricomponent
finalizationregistry
generatorfunction
referenceerror
sharedarraybuffer
uint8clampedarray
addition assignment
async function expression
async function expression
bitwise and assignment
bitwise or assignment
bitwise xor assignment
class expression
comma operator
conditional ternary operator
destructuring assignment
division assignment
exponentiation
exponentiation assignment
function expression
function expression
greater than or equal
grouping operator
left shift assignment
less than or equal
logical and assignment
logical or assignment
multiplication
multiplication assignment
nullish coalescing assignment
nullish coalescing operator
object initializer
operator precedence
optional chaining
property accessors
remainder assignment
right shift assignment
spread syntax
strict equality
strict inequality
subtraction assignment
unary negation
unsigned right shift
unsigned right shift assignment
void operator
async function
async function
block statement
empty statement
expression statement
labeled statement
arrow function expressions
default parameters
method definitions
rest parameters
the arguments object
private properties
public class fields
static initialization blocks
regular expressions
backreference 1 2
character class escape d d w w s s
character escape n u
input boundary assertion
literal character a b
lookahead assertion
lookbehind assertion
modifier imsims
named backreference kname
named capturing group name
noncapturing group
quantifier n n nm
unicode character class escape p p
word boundary assertion b b
aggregateerror no promise in promiseany was resolved
error permission denied to access property x
internalerror too much recursion
rangeerror argument is not a valid code point
rangeerror bigint division by zero
rangeerror bigint negative exponent
rangeerror form must be one of nfc nfd nfkc or nfkd
rangeerror invalid array length
rangeerror invalid date
rangeerror precision is out of range
rangeerror radix must be an integer
rangeerror repeat count must be less than infinity
rangeerror repeat count must be nonnegative
rangeerror x cant be converted to bigint because it isnt an integer
referenceerror x is not defined
referenceerror assignment to undeclared variable x
referenceerror cant access lexical declaration x before initialization
referenceerror deprecated caller or arguments usage
referenceerror must call super constructor before using this in derived class constructor
referenceerror super called twice in derived class constructor
syntaxerror argumentseval cant be defined or assigned to in strict mode code
syntaxerror 0prefixed octal literals are deprecated
syntaxerror use strict not allowed in function with nonsimple parameters
syntaxerror x is a reserved identifier
syntaxerror at end of pattern
syntaxerror a declaration in the head of a forof loop cant have an initializer
syntaxerror applying the delete operator to an unqualified name is deprecated
syntaxerror arguments is not valid in fields
syntaxerror await is only valid in async functions async generators and modules
syntaxerror awaityield expression cant be used in parameter
syntaxerror cannot use unparenthesized within and expressions
syntaxerror character class escape cannot be used in class range in regular expression
syntaxerror continue must be inside loop
syntaxerror duplicate capture group name in regular expression
syntaxerror duplicate formal argument x
syntaxerror forin loop head declarations may not have initializers
syntaxerror function statement requires a name
syntaxerror functions cannot be labelled
syntaxerror getter and setter for private name x should either be both static or nonstatic
syntaxerror getter functions must have no arguments
syntaxerror identifier starts immediately after numeric literal
syntaxerror illegal character
syntaxerror import declarations may only appear at top level of a module
syntaxerror incomplete quantifier in regular expression
syntaxerror invalid assignment lefthand side
syntaxerror invalid bigint syntax
syntaxerror invalid capture group name in regular expression
syntaxerror invalid character in class in regular expression
syntaxerror invalid class set operation in regular expression
syntaxerror invalid decimal escape in regular expression
syntaxerror invalid identity escape in regular expression
syntaxerror invalid property name in regular expression
syntaxerror invalid range in character class
syntaxerror invalid regexp group
syntaxerror invalid regular expression flag x
syntaxerror invalid unicode escape in regular expression
syntaxerror jsonparse bad parsing
syntaxerror label not found
syntaxerror missing after property id
syntaxerror missing after argument list
syntaxerror missing after condition
syntaxerror missing after element list
syntaxerror missing after function body
syntaxerror missing after property list
syntaxerror missing in const declaration
syntaxerror missing formal parameter
syntaxerror missing name after operator
syntaxerror missing variable name
syntaxerror negated character class with strings in regular expression
syntaxerror new keyword cannot be used with an optional chain
syntaxerror nothing to repeat
syntaxerror numbers out of order in quantifier
syntaxerror octal escape sequences cant be used in untagged template literals or in strict mode code
syntaxerror parameter after rest parameter
syntaxerror private fields cant be deleted
syntaxerror property name proto appears more than once in object literal
syntaxerror raw bracket is not allowed in regular expression with unicode flag
syntaxerror redeclaration of formal parameter x
syntaxerror reference to undeclared private field or method x
syntaxerror rest parameter may not have a default
syntaxerror return not in function
syntaxerror setter functions must have one argument
syntaxerror string literal contains an unescaped line break
syntaxerror super is only valid in derived class constructors
syntaxerror tagged template cannot be used with optional chain
syntaxerror unexpected used outside of class body
syntaxerror unexpected token
syntaxerror unlabeled break must be inside loop or switch
syntaxerror unparenthesized unary expression cant appear on the lefthand side of
syntaxerror use of super propertymember accesses only valid within methods or eval code within methods
syntaxerror using to indicate sourceurl pragmas is deprecated use instead
typeerror x is not iterable
typeerror x is not y
typeerror x is not a constructor
typeerror x is not a function
typeerror x is not a nonnull object
typeerror x is readonly
typeerror bigint value cant be serialized in json
typeerror calling a builtin x constructor without new is forbidden
typeerror cant accessset private field or method object is not the right class
typeerror cant assign to property x on y not an object
typeerror cant convert bigint to number
typeerror cant convert x to bigint
typeerror cant define property x obj is not extensible
typeerror cant delete nonconfigurable array element
typeerror cant redefine nonconfigurable property x
typeerror cant set prototype of this object
typeerror cant set prototype it would cause a prototype chain cycle
typeerror cannot use in operator to search for x in y
typeerror class constructors must be invoked with new
typeerror cyclic object value
typeerror derived class constructor returned invalid value x
typeerror getting private setteronly property
typeerror initializing an object twice is an error with private fieldsmethods
typeerror invalid instanceof operand x
typeerror invalid arrayprototypesort argument
typeerror invalid assignment to const x
typeerror iteratorasynciterator constructor cant be used directly
typeerror matchallreplaceall must be called with a global regexp
typeerror more arguments needed
typeerror nullundefined has no properties
typeerror property x is nonconfigurable and cant be deleted
typeerror reduce of empty array with no initial value
typeerror setting getteronly property x
typeerror weakset keyweakmap value x must be an object or an unregistered symbol
typeerror xprototypey called on incompatible type
urierror malformed uri sequence
warning file is being assigned a sourcemappingurl but already has one
warning unreachable code after return statement
javascript technologies overview
lexical grammar
iteration protocols
strict mode
template literals
trailing commas
deprecated features
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SEO Advice for developer.mozilla.org
In this section we provide pointers on how you can to optimize your web page so it can be found more easily by search engines and how to make it rank higher by optimizing the content of the page itself. For each of the individual criteria the maximum score is 100%. A score below 70% is considered to be indication that the page is not complying with general SEO standards and should be evaluated and/or fixed. Not every factor is weighted the same and some are not as important as others. Relatively unimportant factors like meta keywords are not included in the overall score.
Item | Factor | Pointers | |
---|---|---|---|
PageTitle | 100% | Far too many sites lack a page title. A page title is the first thing that shows in the search results so always use the title element. | |
Title relevance | 0% | A title should reflect the contents of a site. This site has a 0 % match | |
Title Length | 10% | Limit your title to anywhere between 40 and 70 characters. Your title was 13 characters long | |
Meta Description | 100% | A meta description is the second element that shows in the search results so always use the meta description. | |
Meta description length | 50% | The meta description should be between 145 and 160 characters. This meta description is 355 characters long. | |
Meta description relevance | 65% | Meta Description should reflect the contents of a site. This site has a 36 % match | |
Number of internal links | 30% | Linking to internal pages makes pages easier to find for search engines. Try to keep the number of links on your page roughly below 100. There are 441 internal links on this page. | |
Folder structure | 100% | We found a folder structure in the links on your page. A good folder structure makes a site easier to navigate. We found 4 level 1 folders and 31 folders above or in the first level of navigation. | |
Headings | 83% | Headers should reflect the contents of a site. This site has a 36 % match | |
Links | 12% | Link anchors should to some degree reflect the contents of a site. This site has a 6 % match | |
No images detected | 60% | This site doesn't seem to use images in the html code. Images can enhance user experience so consider brightening up the page with images. | |
Bold and italic | 100% | Bold and italic tags should reflect the contents of a site to some degree. This site has a 100 % match | |
Html ratio | 60% | Try to keep the html / text ratio as low as possible. More html means longer loading times. Layout should be handled in a serpate css file | |
Page errors | 100% | Pages with no errors display significantly faster on most browsers. We detected 0 errors and warnings | |
WordCount | 20% | An ideal page contains between 400 and 600 words.This page contains 1708 words | |
Server response time | 30% | A slow server slows down a website. This server responds 236.65% slower the average | |
Gzip Compression | 100% | This site uses Gzip compression to display faster | |
Keywords in Domainname | 30% | There are no important keywords in your domain name | |
Keywords in domain path | 100% | There are important keywords in the domain path | |
Structured Data | 100% | Structured data makes it easier for search engines to index your website | |
Inline css | 93% | Do not use inline css declarations. Inline css will slow down the rendering of the website. We detected 2 inline style declarations ( <a style="color:green">) with a size of 51 bytes | |
Excessive use of the same words | 100% | There is no indication that there are one or more keywords that are used excessively. | |
Frames or iframes | 100% | Perfect, detected not (i)frames on your webpagina | |
Flash | 100% | Perfect, we detected no flash objects on your page | |
Css | 100% | Perfect, we did not detect too many CSS files | |
Javascript | 30% | Wij detected too much (2) blocking JavaScript files. Try to combine or defer the loading of JavaScript files | |
Mobile Website | 100% | Perfect, we found a responsive design for mobile users | |
Most important heading | 100% | Perfect, we detected a correct use of the most important (h1) heading! | |
Normalized headings | 40% | We dit not font a normalized heading structure. A heading 2 (h2) for example should be followed by a heading of an equal level (h2), a child heading (h3) or even a aprent heading (h1). |
How would you like to have SEO advice for all your pages ?? Start your SEO Dashboard and optimize your website!
developer.mozilla.org images and descriptions
0 images found at developer.mozilla.org Images can improve the user experience for a website by making a pag visually appealing Images can also add extra keyword relevance to a webpage by using alt tags. Images can also slow down a website. If the width and height for a picture is not specified for a browser know in advance how large the image is. A browser must first load the picture and see before it knows how much space should be on the page. Upon reservation In the meantime, the browser can do little but wait. When the height and width for the plate are given in the HTML code, a browser just continues to build for a page while the images load in the background.
How are images contributing to your SEO site-wise ? Your leading content tool has the awnsers!