Robert 的部落格

如果我已經取得form元素，要如何取得底下的tag呢？

var x = document.getElementById("myForm").elements.length; 

語法：
formObject.elements

屬性：
length

方法：
[index]
item(index)
namedItem(id)

範例：

var x = document.getElementById("myForm").elements[0].value;

var x = document.getElementById("myForm").elements.item(0).value;

var x = document.getElementById("myForm").elements.namedItem("fname").value;

var x = document.getElementById("myForm");
var txt = "";
var i;
for (i = 0; i < x.length; i++) {
    txt = txt + x.elements[i].value + "<br>";
}
document.getElementById("demo").innerHTML = txt;

參考：Form elements Collection

2019/06/03 新增：

2.

document.forms[0]['txtPasswd'].focus(); // 'txtPasswd' 是id名稱.

3.

var inpuForm = document.getElementById("form1").getElementsByClassName("inputField");

參考：https://stackoverflow.com/questions/7815374/get-element-inside-element-by-class-and-id-javascript

取得元素方法總整理：getElementById(), getElementsByTagName(), getElementsByClassName(), getElementsByName(), querySelector(css_selector)
querySelectorAll(css_selector)

var xx = document .querySelectorAll("p");

• div → all div elements.
• div p → all p inside div.
• #y683 → element with id="y683"
• div.xyz → all div has class xyz.
• input[name="pets1"]:checked → all element with name="pets1" and checkbox checked

參考：http://xahlee.info/js/js_get_elements.html