How to add string numbers in javascript

JavaScript is a very popular and commonly used programming language. One of its most commonly used functions is to operate numbers and strings. However, adding string numbers is not very easy in JavaScript. This article will discuss how to add string numbers in JavaScript.

In JavaScript, use the " " operator to add two numbers. For example:

var x = 1;
var y = 2;
var z = x + y;
console.log(z); // 输出3

However, when we try to add two string numbers:

var x = "1";
var y = "2";
var z = x + y;
console.log(z); // 输出"12"

This is because in JavaScript, when we use the " " operator to add two strings When adding, it doesn't convert them into numbers but concatenates them together. That's why the code above outputs "12" instead of the number "3".

So, what should we do if we want to add these two string numbers? The answer is to convert them into numbers first and then add them together. In JavaScript, we can use the parseInt() or parseFloat() function to convert a string into a number. For example:

var x = "1";
var y = "2";
var z = parseInt(x) + parseInt(y);
console.log(z); // 输出3

Alternatively, we can also use the Number() function to convert a string into a number. For example:

var x = "1";
var y = "2";
var z = Number(x) + Number(y);
console.log(z); // 输出3

It should be noted that the behavior of these two functions is slightly different. parseInt()The function will try to convert the string to an integer, and if it cannot be converted, it will return NaN (not a number). The parseFloat() function will try to convert the string into a floating point number, and if it cannot be converted, it will return NaN. Number()The function will try to convert the string into any type of number, including integers, floating point numbers, scientific notation, etc.

In addition to using these functions, we can also use operators - to subtract string numbers. This is because in JavaScript, the - operator can only be used for numbers, so it converts string numbers into numbers and then subtracts them. For example:

var x = "6";
var y = "2";
var z = x - y;
console.log(z); // 输出4

It should be noted that if the string contains non-numeric characters, the conversion will fail and NaN will be returned. For example:

var x = "1a";
var y = "2b";
var z = parseInt(x) + parseInt(y);
console.log(z); // 输出NaN

To avoid this, we should use the isNaN() function to check if they are valid numbers before converting strings to numbers. For example:

var x = "1a";
var y = "2b";
if (!isNaN(x) && !isNaN(y)) {
  var z = parseInt(x) + parseInt(y);
  console.log(z); // 不会输出，因为x和y无效
}

In actual programming, we may encounter situations where we need to add a set of string numbers. At this point, we can use a loop to convert them into numbers one after another and add them together. For example:

var nums = ["1", "2", "3"];
var sum = 0;
for (var i = 0; i < nums.length; i++) {
  var num = parseInt(nums[i]);
  if (!isNaN(num)) {
    sum += num;
  }
}
console.log(sum); // 输出6

In this code, we first define an array containing string numbers. We then use a loop to iterate through each element in the array, convert them into numbers and add them to the variable sum. It should be noted that we use the isNaN() function to check whether they are valid numbers before converting each string.

In short, adding string numbers in JavaScript is not an easy task. However, we can easily accomplish this task as long as we convert them into numbers first and then add them together. Hope this article helps you!

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