如何编写按钮以显示数组的长度？ （在javascript中）

Question

<button onclick="lengthArray()">Item Quantity</button>
<p id="quant"></p>

var products = ["Printer", "Tablet", "Router", "Graphics Card","Cooling Fan"];
function lengthArray() {
    products.length();
    document.getElementById("quant").innerHTML = products.length();
}

Hello! I need some programming a button in javascript that can display the length of the array when the button has been clicked. The code above is my failed attempted to tackle this task, as nothing happens when the said button is clicked. Edit: Thank you guys for helping me out !

Answer 1

Use products.length instead of products.length() for getting length of array

 var products = ["Printer", "Tablet", "Router", "Graphics Card","Cooling Fan"]; function lengthArray() { document.getElementById("quant").innerHTML = products.length; } 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <button onclick="lengthArray()">Item Quantity</button> <p id="quant"></p> 

Answer 2

change your code to:

function lengthArray() {
     document.getElementById("quant").innerHTML = products.length; <<-- Remove "()"
}

Because length isn't a function. it's a property :)

Answer 3

<button onclick="lengthArray()">Item Quantity</button>
<p id="quant"></p>


var products = ["Printer", "Tablet", "Router", "Graphics Card","Cooling Fan"];
function lengthArray() {
    document.getElementById("quant").innerHTML = products.length;
}

Answer 4

Just remove the brackets after length - to get the length of an array you have to use length not length()

this is how your code should look like

document.getElementById("quant").innerHTML = products.length;

and add a button to run the function

<button onclick="lengthArray()">Button</button>

or you could just use your paragraph by adding a text to click on

<p id="quant" onclick="lengthArray()">now visible</p>

---

hope it helps ! ^^

Answer 5

try this:

 var products = ["Printer", "Tablet", "Router", "Graphics Card", "Cooling Fan"]; function lengthArray() { console.log(products.length); } 

 <button onclick="lengthArray()">Item Quantity</button> <p id="quant"></p>