1. Experimental purposes and requirements
Experimental tasks
1. Master the syntax rules of JavaScript
2. Master JavaScript variable declarations
3. Familiar with JavaScript data types
4. Master the various operators of JavaScript
5. Master JavaScript function definitions
Training skill points
- Master variable definitions
- Master the application of if conditional statements
- Master the application of for loop
- Master data type conversion
- Master the definition of parameterized functions
2. Experimental instruments and equipment. Computers
equipped with Dreamweaver , HBuilder and other software, and a smooth network.
3. Experimental tasks and steps
Experiment 1. Output triangle
Statement of needs
Enter the number of rows to print triangles, and print triangles on the page. No matter whether the number of input triangle rows is greater than 8, the number of output triangle rows is at most 8. The triangles output on the page are as shown in the figure:
Figure 1 Enter the number of lines to print Figure 2 Output triangles on the page
Implementation ideas and steps
- Use the prompt() method to enter the number of rows of the triangle, and call the parseInt() method to convert the row number to an integer.
- Use an if statement to determine whether the number of rows is less than 8.
3. Use a double for loop to output the triangle, use the outer loop variable to control the rows , and the inner loop variable to control the number of * numbers in each line . The * number in each line is output and the line breaks .
Experiment 2. Writing functions
Statement of needs
Write the function f(x)=5x^2+9x-15, use the prompt dialog box to input the value of x, and output the corresponding result on the page.
Implementation ideas and steps
1. Define the function and express the function using addition, subtraction and multiplication operators.
2. Use the prompt() method to enter the value of x.
3. Call the defined function.
4. Use the document.write() method to output the corresponding results on the page.
Figure 1 Enter the value of x Figure 2 Output the result on the page
4. Experimental code demonstration
Experiment 1 code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>打印三角形</title>
<style type="text/css">
body{text-align: center;}
</style>
</head>
<body>
<script type="text/javascript">
var row=parseInt(prompt("请输入三角形的行数："));
if(row<=8){
for(var i=0;i<row+1;i++){
for( var j=0;j<i;j++){
document.write("*");
}
document.write("</br>");
}
}
else{
for( var i=0;i<9;i++){
for(var j=0;j<i;j++){
document.write("*");
}
document.write("</br>");
}
}
</script>
</body>
</html>
Experiment 2 code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>计算函数表达式</title>
<script type="text/javascript">
function f(x){
var y=5*x*x+9*x-15;
document.write("结果是"+y);
}
</script>
</head>
<body>
<script type="text/javascript">
var x=parseInt(prompt("请输入一个数"));
f(x);
</script>
</body>
</html>
5. Experimental results
Experiment 1 results:
Enter a number less than 8:
Enter a number greater than 8:
Experiment 2 results:
