Check if INSERT mode is ON when typing in an input

问题

I'm trying to calculate the value of an input field on various events regardless of the event caught.

I'm taking into account the events keypress keyup keydown cut paste events (Do I forget anything?).

I'm trying to determine if the text-input INSERT mode is on (default - on), or off. I cannot determine the mode by capturing a key event of that key, though I don't know what was the initial state.

Does anyone know a way? Preferably - a cross browser solution that includes IE8+, Chrome and FF.

Any solution, or in the words of Barney Stinson, "scam, con, hustle, hoodwink, gambit, flim flam, stratagem, and bamboozle" that could help me would be appreciated.

Thanks in advance.

回答1:

For IE only:

document.queryCommandValue("OverWrite");

As far as I know, Firefox and Chrome don't have overwrite mode. The insert key doesn't work in those browsers, and they are always in insert mode.

Moreover, Mac keyboard doesn't have a insert key from the beginning. So Safari also is always in insert mode.

回答2:

Although I don't think you can directly access the state of the user's Insert status, you can figure out how long the strings are when the user is editing the field.

Consider this, tied with a simple <input id="input" />:

var i = document.getElementById('input');

document.onkeydown = function(e) {
    var c = String.fromCharCode(event.keyCode);

    if(null !== c.match(/\w/)) {
        l = i.value.length;
    }
}

document.onkeyup = function(e) {
    var c = String.fromCharCode(event.keyCode);

    if(null !== c.match(/\w/)) {
        if(l === i.value.length) {
            console.log("Keyboard insert might be off - length hasn't changed");
        }
    }
}

Note that there is a rudimentary check to try and isolate only letters and numbers (with the match against the keyCode (borrowed from here), as you don't want to perform the check against a shift key being pressed, for instance.

Basic POC here: http://jsfiddle.net/Xp3Jh/

I'm certain there are more in-depth checks you can do, but hopefully this helps!

来源：https://stackoverflow.com/questions/18242548/check-if-insert-mode-is-on-when-typing-in-an-input

标签

javascript

javascript-events

keyboard