尝试通过innerHTML理解此JavaScript行为

Question

I'm trying to set the less-than symbol and the less-than or equal symbol using innerHTML , then get the encoded text back out, not the decoded symbols.

This works with < , but not with ≤ . Is there a reason why this would be?

var lt = '<';
var le = '≤';

var div_lt = document.createElement('div');
div_lt.setAttribute('original_value', lt);
div_lt.innerHTML = lt;

var div_le = document.createElement('div');
div_le.setAttribute('original_value', le);
div_le.innerHTML = le;

console.log([div_lt.innerHTML, div_lt.innerText, div_lt.getAttribute('original_value')]);
// gives [ "&lt;", "<", "&lt;" ], as I expected
console.log([div_le.innerHTML, div_le.innerText, div_le.getAttribute('original_value')]);
// gives [ "≤", "≤", "&le;" ], but the first value should be "&le;"

JSFiddle: https://jsfiddle.net/54m6c8sk/

Answer 1

In HTML < means "Start of tag" and ≤ means "≤".

When you want to express < in HTML then you often must use an entity. When you want to express ≤ , you never have to use an entity.

Converting DOM to HTML via innerHTML doesn't convert ≤ to ≤ because it is never useful to do so.

Answer 2

This is a fun one... but already answered: How do I prevent HTML encoding of '&' characters while copying content from a div to the title of the page?

tldr: use textContent instead of innerHTML -- innerHTML is actually not part of the DOM spec