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Solving common JavaScript problems


In this article we'll look at some common javascript problems and how we can solve them. If you've come across these problems, take a practical look at how you can get out of them, or even better, leave comments on how you've solved them. Suppose you have the following code: ```js function som(a, b) { return a + b } var result = soma(3, 4) console.log("The result of the sum is: " result) ``` When you try to run this code, you'll get a syntax error because a plus sign (+) is missing between the string and the variable in the console.log() line. Here's the fix: ```js function sum(a, b) { return a + b; } var result = sum(3, 4); console.log("The result of the sum is: " + result); ``` The code is now corrected. We added the plus sign (+) to concatenate the string with the 'result' variable. This is a simple example of a common syntax error in JavaScript and how to fix it. ## 1. Undefined or Null Variables: A common example is trying to access a property of an object that doesn't exist or accessing a variable that hasn't been defined. Here's an example: ```js var person = { name: "John", age: 30 }; console.log(person.job); // job is not defined in the 'person' object ``` To avoid this type of error, you can check that the property exists before accessing it: ```js if (person.hasOwnProperty('job')) { console.log(person.job); } else { console.log("The property 'job' is not set for this person."); } ``` ## 2. Data Type Errors: In JavaScript, operations between different data types can result in unexpected behavior or errors. For example: ```js var x = "5"; var y = 2; console.log(x + y); // Output: "52" instead of 7 ``` In this case, the + operator is used to concatenate strings when at least one of the operands is a string. To ensure that the operation is a numeric addition, you can convert 'x' to a number: ```js console.log(Number(x) + y); // Output: 7 ``` ## 3. Infinite loops: Infinite loops can occur when the stop condition of a loop is never reached. For example: ```js var i = 0; while (i < 5) { console.log(i); // forgetting to increment i } ``` In this case, 'i' never increases, so the condition i < 5 will always be true, resulting in an infinite loop. To fix this, you need to ensure that the loop's control variable is updated correctly: ```js var i = 0; while (i < 5) { console.log(i); i++; // Increment i to avoid the infinite loop } ``` By correcting these common problems, you can write more robust and less error-prone JavaScript code.

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JavaJuggler
JavaJuggler
0

good repair Mr `fschmidt`, i hadn't even noticed these mistakes! i won't edit the post so others can see the shit i sometimes do :/


fschmidt
fschmidt
0

In example 0, the function is defined as "som" but called as "soma". The 2 solutions are: console.log("The result of the sum is: " + result); console.log(`The result of the sum is: ${result}`); <br> In example 1, the suggested solution doesn't address "access a property of an object that doesn't exist" which would still throw an error. In general, I wouldn't add any of this error handling code, I would just fix the error. That keeps the code simple. <br> Example 2 is fine. <br> The better solution to example 3 is: for( let i = 0; i < 5; i++ ) { console.log(i); }