javascript函数，如何在document.write中获取变量？

Question

I need to call a variable inside a document.write but it doesnt work... example

function(){
    var variable=document.getElementById("text");
    alert("your text "+ variable);
}

inside a table there is:

document.write('<td><input type="text" id="example"></td>');<br>
document.write('<td><input type="button" value="enter a text" onclick="function()">

Answer 1

Anonymous functions like below are allowed in javascript but we cannot call them by using function(){} from an element etc at a later time. They need to have a reference, in your case just a name after function will do

function(){        
  //Your code
} 

Becomes

function myFunction(){ //myFunction can be changed to another more suitable name
  //Your code here;
}

Then from your document.write statement call your named function in the onclick event

document.write('<td><input type="text" id="example"></td>');<br>
document.write('<td><input type="button" value="enter a text" onclick="myFunction()"> 

now that you aren't using function() which is a reserved word in javascript but using myFunction() which javascript now thinks is your named function, it should work

Answer 2

function是保留关键字，不能将其用作函数名。

Answer 3

var newFunction = function(){
    var variable=document.getElementById("text");
    alert("your text "+ variable);
}
document.write('<td><input type="button" value="enter a text" onclick="newFunction()">

Answer 4

You'll need to reference which property of the Element you want to read. Simply using getElementById will return the object, not the value of the textfield. Use getelementById('text').value .

Answer 5

Not sure how much of your code there is real, and how much is just an example, but you need to double-check for your getElementById() and check that the ID you are providing is actually in the HTML.

In your example you show getElementById("text") but then don't have any HTML with an ID of text

Also, if you want to extract the content that is being stored inside that variable, you might want to get its value via getElementById("text").value

The main issue though, seems to be that you're using function(){} - you should name your function, for instance: function foo(){} and then use onclick='foo()' to call it.

Answer 6

function is a reserved keyword.

You can use it like this

var func = function(){
    var variable=document.getElementById("text");
    alert("your text "+ variable);
}

onclick="func()"