How to limit the textarea to only hold numbers?

Question

I\'m trying to make a date textbox on my blog, and the date is only numbers. I don\'t want anybody making a mistake typing a letter. Is there any way to limit the characters

Answer 1

You should use this function to set input filters on various DOM elements including textarea

function setInputFilter(textbox, inputFilter) {
        ["input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop"].forEach(function(event) {
            textbox.addEventListener(event, function() {
                if (inputFilter(this.value)) {
                    this.oldValue = this.value;
                    this.oldSelectionStart = this.selectionStart;
                    this.oldSelectionEnd = this.selectionEnd;
                } else if (this.hasOwnProperty("oldValue")) {
                    this.value = this.oldValue;
                    this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
                } else {
                    this.value = "";
                }
            });
        });
    }

Then you simply set the filter, like that:

setInputFilter(document.getElementById("textarea_id"), value => {
        return /^\d*$/.test(value); // Allow digits and '.' only, using a RegExp
});