因为这正是规范所规定的。数字输入可以接受浮点数，包括负号和e或e字符(其中指数是e或e后面的数字):

A floating-point number consists of the following parts, in exactly the following order: Optionally, the first character may be a "-" character. One or more characters in the range "0—9". Optionally, the following parts, in exactly the following order: a "." character one or more characters in the range "0—9" Optionally, the following parts, in exactly the following order: a "e" character or "E" character optionally, a "-" character or "+" character One or more characters in the range "0—9".

强制使用仅由数字组成的数字的最佳方法:

<input type="number" onkeydown="javascript: return ['Backspace'，'Delete'，'ArrowLeft'，'ArrowRight'].includes(event.code) ?isNaN(Number(event.key)) && event.code!= =‘空间’" / >

这避免了'e'， '-'， '+'， '。“…所有不是数字的字符!

若要只允许数字键，请使用数字函数转换为数字。如果不是数字，则结果为NaN:

isNaN(当家(基)事件。

但接受退格，删除，左箭头，右箭头:

[个’,‘删除’‘ArrowLeft’,‘ArrowRight includes(事件。代码)

这是为允许空格的Firefox设置的:

event.code != =“空间”

要隐藏字母e和负号，可以这样做:

onkeydown="return event.keyCode !== 69 && event.keyCode !== 189"

<input type="number" onkeydown="return FilterInput(event)" onpaste="handlePaste(event)"  >

function FilterInput(event) {
    var keyCode = ('which' in event) ? event.which : event.keyCode;

    isNotWanted = (keyCode == 69 || keyCode == 101);
    return !isNotWanted;
};
function handlePaste (e) {
    var clipboardData, pastedData;

    // Get pasted data via clipboard API
    clipboardData = e.clipboardData || window.clipboardData;
    pastedData = clipboardData.getData('Text').toUpperCase();

    if(pastedData.indexOf('E')>-1) {
        //alert('found an E');
        e.stopPropagation();
        e.preventDefault();
    }
};

E代表指数，用来缩短长数字。因为输入是数学输入而指数在数学中是用来缩短数字的，所以这里有个E。

显示如下:4e。

链接:1和2

角;与IDE keyCode弃用警告

功能上与rinku的答案相同，但有IDE警告预防

numericOnly(event): boolean {
    // noinspection JSDeprecatedSymbols
    const charCode = (event.which) ? event.which : event.key || event.keyCode;  // keyCode is deprecated but needed for some browsers
    return !(charCode === 101 || charCode === 69 || charCode === 45 || charCode === 43);
}