localStorage undefined

with this function :

function appendToStorage(name, data) {
    var old = localStorage.getItem(name);
    if (old === null) old = '';
    localStorage.setItem(name, old + data);
}
appendToStorage('oldData', $('textbox').value);

and this html :

<textarea name ="textbox" cols="50" rows="5">
say it...
</textarea><br>

<input type="submit" onclick="appendToStorage(name, data)"/>

I get undefinedundefinedundefined... on the console.

what I am missing?

---

You need to pass the textarea's value, and the storage key to appendToStorage .

So it is better to use a another method which does that an call that on click of the button like

<input type="submit" onclick="addTextArea();" />

then

function appendToStorage(name, data) {
    var old = localStorage.getItem(name);
    if (old === null) old = '';
    localStorage.setItem(name, old + data);
}
addTextArea();

function addTextArea() {
    appendToStorage('oldData', $('textarea[name="textbox"]').val());//use .val() to get the value, also need to use attribute selecotr for name
}

Demo: Fiddle

---

很难告诉你要在这里实现什么，但最简单的解决方案是让appendToStorage函数完成这项工作：

function appendToStorage (name) {
  
  // get the target element by it's name
  var el = document.querySelector('[name="' + name + '"]');
  
  // check we're getting the correct info
  console.log("[" + name + "]:", el.value);
  
  // save it to storage (you may also want to retrieve the last value and append it)
  window.localStorage.setItem(name, el.value);
}

input {display: block; margin: 0 0 1em; } pre { font-size: 0.9em; display: block; margin: 0.5em 0; }

<script>console.log = function () { document.getElementById("output").innerHTML = Array.prototype.slice.call(arguments).join(" "); }</script>
<textarea name="textbox" cols="50" rows="3">
say it...
</textarea>
<input type="submit" onclick="appendToStorage('textbox')"/>
<textarea name="textbox-again" cols="50" rows="3">
say it again...
</textarea><br>
<input type="submit" onclick="appendToStorage('textbox-again')"/>
<pre id="output"></pre>

链接地址: http://www.djcxy.com/p/36276.html

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