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標籤：尋找 charset 定義 doc function console 等於 htm pre
1 <!DOCTYPE html> 2 <html> 3 <head lang="en"> 4 <meta charset="UTF-8"> 5 <title></title> 6 </head> 7 <body> 8 <script> 9 //定義indexOf函數10 //可以從指定位置開始,尋找下一個指定值得下標位置11 //如果找不到,返回-1;12 var arr=[1,2,3,2,1];13 function indexOf(arr,val,fromi){14 //如果fromi是undefined就賦值為0;15 fromi===undefined&&(fromi=0);16 //從fromi開始,遍曆arr中剩餘元素17 for(var i=fromi;i<arr.length;i++){18 //如果當前元素等於val19 if(arr[i]==val){20 return i; //返回i21 }22 }23 return -1;//返回-124 }25 //在arr中從0位置開始找下一個元素值為2的位置;26 console.log(indexOf(arr,2,0)); //127 //在arr中從2位置開始找下一個元素值為2的位置28 console.log(indexOf(arr,2,2)); //329 //在arr中從4位置開始找下一個元素值為2的位置30 console.log(indexOf(arr,2,4)); //-131 //在arr中從0位置開始找下一個元素值為4的位置32 console.log(indexOf(arr,4,0)); //-133 </script>34 </body>35 </html>
JavaScript-indexOf函數
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