How to search for string in html files using Javascript?

问题

I have 5 html files and I have a search form that I would like to use to search for text in these html files .

<form>
   <input type ='text' />
   <input type ='submit' />
</form>

I have an idea of using xmlhttprequest to get the files

var xhr = new XMLHttpRequest();
xhr.open("GET", "file1.html", false);
xhr.send();
var guid = xhr.responseText;

var xhr = new XMLHttpRequest();
xhr.open("GET", "file2.html", false);
xhr.send();
var guid = xhr.responseText;

...

then search for text in these files but I don't know how to search in the files using javascript.

How to search the files after getting it using xmlhttprequest ? Or Is there is another way to do the search using javascript ?

回答1:

I'd use the DOMParser to make sure we're doing some "smart" searching. Let's say you are looking for texts about the word "viewport"; you don't want any HTML file that has the <meta> tag "viewport" to return as a valid result, would you?

Step one is parsing the string to a Document instance:

const parseHTMLString = (() => {
  const parser = new DOMParser();
  return str => parser.parseFromString(str, "text/html");
})();

Put a valid HTML string in here, and you'll get a document in return that behaves just like window.document! This means we can do all kinds of cool stuff like using querySelector and properties like innerText.

The next step is to define what we want to search. Here's an example that joins in a document's title and body text:

const getSearchStringForDoc = doc => {
  return [ doc.title, doc.body.innerText ]
   .map(str => str.toLowerCase().trim())
   .join(" ");
};

Pass your parsed document to this function, and you'll get a plain string in return that features just content, without attributes, tag names and meta data.

Now, it's a matter of defining the right search method. Could be a RegExp based match, or just a (less fast) split & includes:

const stringMatchesQuery = (str, query) => {
  return query
    .toLowerCase()
    .split(/\W+/)
    .some(q => str.includes(q))
};

Chain those methods together and you got the conversion like:

String -> Document -> String -> Boolean

If you ever want to include more information in the search content, you just update the getSearchStringForDoc function using the standardized API.

A running example (that's a bit messy and could do with some refactoring, but hopefully gets the point across):

const htmlString =  (
`<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>The title</title>
</head>
<body>
  Some text about an interesting thing.
</body>
</html>`);

const parseHTMLString = (() => {
  const parser = new DOMParser();
  return str => parser.parseFromString(str, "text/html");
})();

const getSearchStringForDoc = doc => {
  return [
    doc.title,
    doc.body.innerText
  ].map(str => str.trim())
   .join(" ");
};

const stringMatchesQuery = (str, query) => {
  str = str.toLowerCase();
  query = query.toLowerCase();
  
  return query
    .split(/\W+/)
    .some(q => str.includes(q))
};

const htmlStringMatchesQuery = (str, query) => {
  const htmlDoc = parseHTMLString(str);
  const htmlSearchString = getSearchStringForDoc(htmlDoc);
  
  return stringMatchesQuery(htmlSearchString, query);
};

console.log("Match 'viewport':", htmlStringMatchesQuery(htmlString, "viewport"));
console.log("Match 'Interesting':", htmlStringMatchesQuery(htmlString, "Interesting"));

回答2:

First, change:

<input type ='text' />

To:

<input id= 'text' type='text' />

Then, the code below will create an array called 'files' made up of objects. The 'position' property of each object will contain either the position of 'text' within 'filename', -1 if the text is not found, or -2 if the file did not load.

var text = document.getElementById('text' )

loadCount = 0;
files = [];
files[ 0 ] = {};
files[ 0 ][ 'filename' ] = "file1.html";
files[ 1 ] = {};
files[ 1 ][ 'filename' ] = "file2.html";
files[ 2 ] = {};
files[ 2 ][ 'filename' ] = "file3.html";
files[ 3 ] = {};
files[ 3 ][ 'filename' ] = "file4.html";
files[ 4 ] = {};
files[ 4 ][ 'filename' ] = "file5.html";

function search( item, index ) {

  xmlhttp.onload = function () {
    var files[ index ][ 'contents' ]  = xhr.responseText;
    if ( typeof files[ index ][ 'contents' ] !== 'undefined' ) {
      files[ index ][ 'position' ] = str.indexOf( text );
    } else {
      files[ index ][ 'position' ] = -2;
    }
    loadCount = loadCount + 1;
    if ( loadCount == 5 ) {
      // do whatever you want here
    }
  }

  var xhr = new XMLHttpRequest();
  xhr.open( "GET", item[ 'filename' ], false );
  xhr.send();

}

files.forEach( search );

来源：https://stackoverflow.com/questions/46816443/how-to-search-for-string-in-html-files-using-javascript

标签

javascript

html

html5

dom

xmlhttprequest