TypeScript: Property "value" does not exist on type "HTMLElement"

Little scum · Posted on 5/27/2019 2:06:54 PM

The html looks like this:

and greeter.ts Documents:

When I compile with tsc I get the following "error":

/home/bjarkef/sandbox/greeter.ts(8,53)：属性’value’不存在类型’HTMLElement’的值，

However, the compiler outputs a javascript file, which works fine in chrome.

How did I get this error? How can I fix it?

Also, where can I find which properties are valid in "HTMLElement" according to typescript?

Note that I'm very new to JavaScript and typescript, so I might be missing something noticeable.

Based on Tomasz Nurkiewiczs' answer, the "problem" is that typescript is type-safe. :) so the type HTMLElement returned by document.getElementById() does not contain the value property. However, the HTMLInputElement subtype contains the value property.
So a solution is to convert the result of getElementById() to HTMLInputElement like this:

Login is visible.

<> is the casting operator in the typescript.

The javascript generated from the above line looks like this:

Login is visible.

That is, it does not contain type information.

[TypeScript] TypeScript: Property "value" does not exist on type "HTMLElement"

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