How do I concatenate a string with a variable in JavaScript to create a new string?

Concatenating Strings with Variables in JavaScript

In JavaScript, concatenating a string with a variable requires specific syntax. This tutorial addresses the common question of how to combine a string and a numeric variable to create a new string.

Original Question:

The user wishes to create a string by combining a string, "horseThumb," and a passed numeric variable, "id," but faces difficulties.

Answer and Troubleshooting:

The code provided in the question is correct. However, there could be other issues affecting the desired outcome.

1. Passing an ID to the Function: Ensure that you are passing an ID value as an argument to the function call.
2. Element Existence: Verify that an element with the ID specified in the variable exists within the document's DOM.
3. Browser Loading: If you are trying to access the element before the page has fully loaded, you may encounter issues. Place the function call inside an onload event handler to address this.

Using Template Literals:

Since ECMAScript 2015, template literals (template strings) offer an alternative method for concatenation:

document.getElementById(`horseThumb_${id}`).className = "hand positionLeft";

Debugging Assistance:

To identify the source of the problem, add these lines to the beginning of the function:

alert('ID number: ' + id);
alert('Return value of gEBI: ' + document.getElementById('horseThumb_' + id));

These pop-up windows will provide information regarding the passed ID and the element's existence.

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