Is there a Regular expression to match the html string that can not render any text?

Question

As the title shows.

const reg = //i  //what should the regular expression be?

let HTML = ''; // true

html = '<p></p>' // true
html = '<p> </p>' // true
html = '<p><p></p></p>' // true
html = '<div><br></div>' // true
html = '<div><br/></div>' // true
html = '<div>&nbsp;</div>' // true
html = '<p>a</p><p></p>' // false

reg.test(HTML)

Or are there any other methods to match the string like that?

Thank you!

Answer 1

Since you're using Javascript, you could turn the text into a document, then take the document's textContent , trim it, and check to see if it's the empty string:

 const test = str => new DOMParser() .parseFromString(str, 'text/html') .documentElement .textContent .trim() === ''; console.log(test('<p></p>')); // true console.log(test('<p> </p>')); // true console.log(test('<p><p></p></p>')); // true console.log(test('<div><br></div>')); // true console.log(test('<div><br/></div>')); // true console.log(test('<div>&nbsp;</div>')); // true console.log(test('<p>a</p><p></p>')); // false

( DOMParser is used instead of just assigning the HTML as the innerHTML of an element, because the innerHTML method can allow for arbitrary code execution, which is unsafe)