10.27js代码


<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>符攀飞数组的练习1例题</title> </head> <body> <script> var arr=['苹果','橘子','香蕉','桃子',]; console.log(arr[0]); console.log(arr[1]); console.log(arr[2]); console.log(arr[3]); console.log(arr[4]);//这个undefined没有找到 </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>符攀飞数组的练习2:遍历数组</title> </head> <body> <script> var arr = [80,75,69,95,92,88,76]; var sum =0; for (var i=0;i<arr.length;i++)//数组名.length来快速获取数组长度 { sum=sum+arr[i]; } var avg=sum/arr.length; console.log('avg的值为:'+avg.toFixed(2));//平均分结果保留两位小数 </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>符攀飞3:数组元修改数组长度</title> <script> // var arr =['a','b','c'] // console.log(arr.length); var arr1=[1,2]; arr1.length =4; console.log(arr1); var arr2=[1,2,3,4]; arr2.length =2; console.log(arr2); </script> </head> <body> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>符攀飞04:数组转化成字符串</title> </head> <body> <script> var arr=['red','green','blue','pink']; var str = arr[0];// var sep = '|'; for(var i =1;i<=arr.length-1;i++) { str=str+sep+arr[i]; } console.log(str); </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>符攀飞05:增加或修改数据元素</title> </head> <body> <script> var arr=['red','red','blue']; arr[3] ='pink';//新增数列元素 console.log(arr); arr[0]='yellow';//修改数组 console.log(arr); </script> </body> </html>
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