html - Getting the values of textboxes in Javascript - Stack Overflow

admin管理员组

文章数量:1399006

I have this html code:

<table border="" cellpadding="3" cellspacing="0" id="mytable">

<tbody><tr><td>Song:</td> <td><input type="text" name="song" maxlength="64" size="48" /> </td></tr>
<tr><td>Artist:</td> <td><input type="text" name="artist" maxlength="16" size="48" /> </td></tr>

How do I get the values of "song" and "artist"? I have tried:

var elTableCells = mytable.getElementsByTagName("td");
alert(elTableCells[2].value);
alert(elTableCells[4].value);

but I keep getting "undefined" even when there is text inside the textbox

I have this html code:

<table border="" cellpadding="3" cellspacing="0" id="mytable">

<tbody><tr><td>Song:</td> <td><input type="text" name="song" maxlength="64" size="48" /> </td></tr>
<tr><td>Artist:</td> <td><input type="text" name="artist" maxlength="16" size="48" /> </td></tr>

How do I get the values of "song" and "artist"? I have tried:

var elTableCells = mytable.getElementsByTagName("td");
alert(elTableCells[2].value);
alert(elTableCells[4].value);

but I keep getting "undefined" even when there is text inside the textbox

• javascript
• html
• html-table
• textbox

Share Improve this question Follow edited Jul 29, 2017 at 22:40 Brian Tompsett - 汤莱恩 5,8937272 gold badges6161 silver badges133133 bronze badges asked Jan 18, 2011 at 21:52 Franz PayerFranz Payer 4,1371616 gold badges5555 silver badges7878 bronze badges

Add a ment  | 

6 Answers 6

Sorted by: Reset to default 4

First, td elements don't have a value attribute, so calling .value on them won't do a thing. Second, the value is actually on the input element, so you need to do mytable.getElementsByTagName('input') instead. Even better would be to give your input fields ids and then use getElementById. This would mean you could alter your HTML without your JS breaking.

The tagName that is relevant here is "input", not td. That will get you what you're looking for.

It's almost a cliche on StackOverflow, but I suggest you take a look at JQuery. JQuery allows you to treat your html as a database and query it to get this kind of stuff. If your markup was like this:

<input type="text" id="song" maxlength="64" size="48" />

You could get the value like this:

$("#id").value();

If you wanted to get the value of the maxlength attribute on it, you could do this:

$("#id").attr("maxlength");

Much more fun than digging through element arrays.

var song   = document.getElementsByName("song").value;
var artist = document.getElementsByName("artist").value;

Download jquery

jQuery("input[name='song']").val()

To try and resolve the argument below. This can be down with plain javascript as above but for simplicity and cross browser standardisation I would remend jQuery. It is a widely used and generally highly remended library.

alert(document.getElementsByName("song")[0].value);
alert(document.getElementsByName("artist")[0].value);

I find this to work effectively, Below I am getting a date from an asp textbox and then getting today's date. I then send both dates through a function to get the number of months that I need to do my calculation (be aware that the code uses Infragistics libraries (if you intent to copy and paste, replace those calls with standard JavaScript calls):

function calculateMonthlyRepayment() 

    var tStartDate = $find('dp_Start_Date');
    var startDate = tStartDate.get_value();
    var today = new Date();
    var numMonths = monthDiff(startDate, today);     
    var rate = igedit_getById('WebNumericEdit_InterestRate').getValue() * 0.01;
    var intRate = (rate / 100) / 12;
    var principal = igedit_getById('WebCurrencyEdit_Proposed_Owing').getValue();
    var repayment = (principal * (Math.pow((1 + intRate), numMonths)) * intRate / (Math.pow((1 + intRate), numMonths) - 1));

    igedit_getById('txt_Monthly_Repayment').setValue(repayment);

}
function monthDiff(d1, d2) {
    var months;
    months = (d2.getFullYear() - d1.getFullYear()) * 12;
    months -= d1.getMonth() + 1;
    months += d2.getMonth();
    return months <= 0 ? 0 : months;
}

本文标签： htmlGetting the values of textboxes in JavascriptStack Overflow