When using Javascript's querySelector, often times it returns null

Question

When using Javascript's querySelector, often times it returns null

Here is the HTML code I am working with:

<button class="pop-btn">
  Pop 
</button>

While I was able to style this button using CSS, I encountered a problem when trying to select it in Javascript:

const Population_div_Button=document.querySelector(".pop-btn");

Population_div_Button.addEventListener("click", function(){
    Open_Populationdiv();
});

The function Open_Populationdiv() is defined by me. Although all seems to be set up correctly, I keep receiving an error message in the console and the script fails to execute:

Uncaught TypeError: Population_div_Button is null http://127.0.0.1:5500/app.js:6

javascript html css

Answer 1

Answer №1

One reason for the error occurring is that the function is being executed before the Document Object Model (DOM) is fully loaded, resulting in the div element being null when the event listener is added.

To prevent this issue, you can include a conditional statement to check if the div element exists before proceeding with adding the event listener:

if(Population_div_Button !== null){
   Population_div_Button.addEventListener("click", function(){
       Open_Populationdiv();
   });
}

Answer 2

One reason for the error occurring is that the function is being executed before the Document Object Model (DOM) is fully loaded, resulting in the div element being null when the event listener is added.

To prevent this issue, you can include a conditional statement to check if the div element exists before proceeding with adding the event listener:

if(Population_div_Button !== null){
   Population_div_Button.addEventListener("click", function(){
       Open_Populationdiv();
   });
}

When using Javascript's querySelector, often times it returns null

Answer №1

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