javascript：在另一个函数中获取函数的变量值 [英] javascript: get a function's variable's value within another function

问题描述

 < input type =textvalue =hahaid = FULL_NAME/> 
  

脚本中的这段代码

 < script language =javascripttype =text / javascript> 
函数first（）{
 var nameContent = document.getElementById（'full_name'）。value; 
 
 
函数second（）{
 first（）; 
 y = nameContent; 
 alert（y）; 
} 
秒（）; 
< / script> 
  

我想要一个显示元素full_name的值的警报，但它似乎不起作用，有谁知道为什么？ ：S

解决方案

nameContent 只存在于 first（）函数，正如您在 first（）函数中定义的那样。

<为了使其作用域更广泛，请在函数之外定义它：

  var nameContent; 
 
函数first（）{
 nameContent = document.getElementById（'full_name'）。value; 
 
 
函数second（）{
 first（）; 
 y = nameContent;警报（Y）; 
} 
秒（）; 
  

稍好的方法是 return 这个值，因为全局变量非常快速地变得混乱：

pre $函数getFullName（）{
return document.getElementById（' 。FULL_NAME'）值;


函数doStuff（）{
var name = getFullName（）;

alert（name）;
}

doStuff（）;

okay so I have this code in body:

<input type="text" value="haha" id="full_name"/>

And this code in script

<script language="javascript" type="text/javascript">
    function first(){
        var nameContent=document.getElementById('full_name').value;
    }

    function second() {
        first();
        y=nameContent; 
        alert(y);
    }
    second();
</script>

I want a alert showing the value of the element full_name, but it doesn't seem to work, does anyone know why? :S

解决方案

nameContent only exists within the first() function, as you defined it within the first() function.

To make its scope broader, define it outside of the functions:

var nameContent;

function first(){
    nameContent=document.getElementById('full_name').value;
}

function second() {
    first();
    y=nameContent; alert(y);
}
second();

A slightly better approach would be to return the value, as global variables get messy very quickly:

function getFullName() {
  return document.getElementById('full_name').value;
}

function doStuff() {
  var name = getFullName();

  alert(name);
}

doStuff();

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