Printing rhombus using JavaScript

The rhombus is one of the more interesting geometric shapes. This article will introduce how to use JavaScript to print rhombuses.

First of all, we need to understand what a rhombus is. A rhombus, also known as a grid polyhedron, is a type of quadrilateral with two sets of opposite parallel lines and four equal interior angles. To print diamonds on a web page, we need to use JavaScript to handle the display logic.

The idea of ​​printing a diamond is to use nested for loops. Suppose we need to print a diamond with n rows, then the process of printing a diamond can be divided into three parts. First, the upper part of the rhombus is printed, then the middle part of the rhombus is printed, and finally the lower part of the rhombus is printed.

The code is as follows:

function printDiamond(n) {
  if (n % 2 === 0) {
    // 如果输入的n是偶数，则加1变成奇数
    n++;
  }
  let middleIndex = Math.floor(n / 2); // 中间的索引
  let diamond = ""; // 菱形字符串

  // 上半部分
  for (let i = 0; i <= middleIndex; i++) {
    for (let j = 0; j < middleIndex - i; j++) {
      diamond += " "; // 打印左上角的空格
    }
    for (let j = 0; j < 2 * i + 1; j++) {
      diamond += "*"; // 打印上半部分的星号
    }
    diamond += "
"; // 换行
  }

  // 中间部分
  for (let i = middleIndex - 1; i >= 0; i--) {
    for (let j = 0; j < middleIndex - i; j++) {
      diamond += " "; // 打印右上角的空格
    }
    for (let j = 0; j < 2 * i + 1; j++) {
      diamond += "*"; // 打印中间部分的星号
    }
    diamond += "
"; // 换行
  }

  console.log(diamond); // 输出菱形
}

In the above code, we define a function printDiamond(n), which is used to print a diamond with n rows. First, by judging the parity of n, if it is an even number, add 1 to make it an odd number to ensure the symmetry of the rhombus. Then the variable middleIndex is defined to represent the middle index of the diamond, and the variable diamond represents the final diamond string to be output.

Next, use nested for loops to print diamond shapes. First, print the upper half of the diamond. Two for loops are used here. The first for loop controls the number of lines, and the second for loop prints the space in the upper left corner and the asterisk in the upper half. Then print the middle part of the diamond. Two for loops are also used here. The first for loop controls the number of lines, and the second for loop prints the space in the upper right corner and the asterisk in the middle part. Finally, the lower half of the diamond is printed. The code for this part is the same as the upper half, except for the number of loops and the characters printed.

Finally, after the diamond printing is completed, we output the diamond string to the console through the console.log(diamond) statement.

Use the following code to call this function to print diamonds:

printDiamond(5);

The running results are as follows:

  *  
 *** 
*****
 *** 
  *  

In actual application scenarios, we can also use this function Use in conjunction with HTML and CSS for better results. The content introduced in this article is only the basic idea of ​​using JavaScript to print diamonds. Readers can use it flexibly according to their actual needs.

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