@desertnet/html-parser
v1.0.1
Published
HTML parser and non-strict validator
Downloads
19,603
Readme
html-parser
This HTML parser and validator is not a strict HTML parser in the vein of the XHTML strict validators of old. Instead, it aims to parse HTML as browsers do and only surface errors that are likely to confuse browsers or that are indicative of a confused HTML author.
Installation
npm install --save @desertnet/html-parser
Usage
const HTMLParser = require('@desertnet/html-parser')
const html = `
<p>
<b>I forgot to close my b tag.
</p>
<p>
I&npsb;misspelled the no-break-space entity.
</p>
`.trim()
const errors = HTMLParser.validate(html)
errors.forEach(error => {
console.log(`${error.message} (line: ${error.line}, column: ${error.column})`)
})
Outputs:
Could not find closing tag for "<b>". (line: 2, column: 3)
Unexpected closing tag, "</p>". Expected closing tag for "<b>". (line: 3, column: 1)
Invalid HTML entity name for "&npsb;". (line: 6, column: 5)
API
HTMLParser.validate(htmlString)
Static method on HTMLParser
constructor. It parses the HTML fragment in htmlString
and returns an array of HTMLParseError
s. If there were no errors, an empty array is returned.
HTMLParser
The HTMLParser
constructor. It takes no arguments.
const parser = new HTMLParser()
.parse(htmlString)
Parses the HTML fragment in htmlString
and returns an HTMLNode
object containing the parsed HTML.
const parseTree = parser.parse('<h1>Hello world!</h1>')
HTMLParseError
Represents an error discovered durning parsing of an HTML fragment.
parseTree.errors.forEach(error => {
console.log(`${error.message} (line: ${error.line}, column: ${error.column})`)
})
.message
Property that is a string containing an English description of the error.
.startIndex
Property that is a number indicating the index into the source string where the error begins.
.endIndex
Property that is a number indicating the index into the source string where the error ends.
.line
Property that is a number indicating the line number where the error begins. Line numbers being at 1
, not 0
.
.column
Property that is a number indicating the column of the line where the error begins. Columns also begin at 1
, not 0
.
HTMLNode
The base class for all node types. Returned by HTMLParser
's .parse
method.
console.log(indentedNodeList(parseTree))
function indentedNodeList (node, indent = '') {
let str = ''
if (node.children) {
str += node.children.reduce((prev, child) => {
return prev + indentedNodeList(child, `${indent} `)
}, '')
}
return `${indent}${node.type}\n${str}`
}
.type
Property indicating the type of node. It will be one of the following strings:
ROOT
: Root node of the tree.TAG
: An HTML tag.ATTRIBUTE
: An attribute of an HTML tag.TEXT
: A text content node.ENTITY
: An HTML entity (i.e.&
)COMMENT
: An HTML comment tag.CLOSETAG
: A closing HTML tag.
.children
Property that is either null
, or an array of HTMLNode
s that are the node's children.
.indexRange
Property that, if non-null, will be an array of two numbers. The first is the index of the source string where the node begins, and the second is the index of the source string where the node ends.
.errors
Property that is an array of HTMLParseError
s associated with this node and its descendants.
.ownErrors
Property that is an array of HTMLParseError
s associated with only this node (not its descendants).
.tagName
On TAG
and CLOSETAG
type nodes, this is a string of the lowercased tag name.
.attributes
On TAG
type nodes, this is an array of ATTRIBUTE
nodes that belong to the tag.
.closingTag
On TAG
type nodes, this is a CLOSETAG
node, if a closing tag for this node was found.