如何自动递增，如果我在 text1 上键入 2015，text2 应该显示 2016。

Question

我想要这个，如果我在 text1 上输入 2015，text2 应该显示 2016

Answer 1

function onkey() { var year1 = document.getElementById("year1"); var s = year1.value; var year2 = document.getElementById("year2"); year2.value = +s + 1;}

Answer 2

也许你只想这样做：let doc, html, bod, I; // for use on other loadsaddEventListener('load', ()=>{doc = document; html = doc.documentElement; bod = doc.body; I = id=>doc.getElementById(id);const year1 = I('year1'), year2 = I('year2');year1.oninput = function(){&nbsp; let v = this.value;&nbsp; if(v.match(/^[0-9]+$/)){&nbsp; &nbsp; year2.value = +v+1;&nbsp; }&nbsp; else if(v === ''){&nbsp; &nbsp; year2.value = '';&nbsp; }}}); // end load<input id='year1' type='number' value='' /><input id='year2' type='number' value='' />