[英]How to check if the user has entered the value of date or not in Javascript?
你必須使用
if(date.value.length == 0)
不是
if(date.length==0)
var f = document.querySelector("form"); f.addEventListener("submit", function(e){ var d = document.getElementById("date"); if(d.value.length < 1){ alert("Date Is Required"); e.preventDefault(); } });
<form> <input type="date" id="date" name="date"> <button>Go</button> </form>
或嘗試這種方式
var f = document.querySelector("form"); f.addEventListener("submit", function(e){ const d = document.getElementById("date"); if(!d.checkValidity()){ alert("Date Is Required"); e.preventDefault(); } });
<form novalidate> <input type="date" id="date" name="date" required> <button>Go</button> </form>
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