js数组基础
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<html><head><meta charset="UTF-8"><title></title></head><body><script type="text/javascript">//計算給定數組arr中所有元素的總和function sum(arr){var result = 0;for(var i = 0; i<arr.length;i++){result = result + arr[i];}console.log(result);}sum([1,2,3]);//合并數組arr1和數組arr2，不要直接修改數組，結果返回新的數組function concat(arr1,arr2,arr3){var arr4 = arr1.concat(arr2,arr3);console.log(arr4);}concat(["s"],["a","b"],[1,3])//刪除數組arr第一個元素，不要直接修改數組arr，結果返回新的數組function deletes(arr){var arr2 = arr.slice(0);arr2.shift();console.log(arr2);}deletes(["s","d","c"])//在數組arr開頭添加元素item，不直接修改數值arrfunction preAddItem(arr,item){var arr2 = arr.slice(0);arr2.unshift(item)console.log(arr2);}preAddItem(["a","b","c"],"a");//移除數組arr中的所有值與item相等的元素，直接在給定數組上操作，并將結果返回function removeItem(arr,item){for(var i=0;i<arr.length;i++){if(arr[i]==item){arr.splice(i,1);i--;}}console.log(arr);}removeItem(["a","b","c","a"],"a");//移除數組的第三個元素，并在數組第三個位置添加新元素:(替換元素，把c替換成e，f)//2代表從刪除數組元素的開始位置（從何處添加/刪除元素。），1代表刪除數組是的元素個數，"e""f"代表添加的元素；//array.splice(index,num),num可以為0，即刪除0個元素；此方法改變的為原數組內容function removeAdd(){var arr = ["a", "b", "c", "d"];var arrRemove = arr.splice(2,1,"e","f");console.log(arr);console.log(arrRemove);//輸出刪除的元素內容，即"c";
}removeAdd();//找出元素item在給定數組arr中的位置function indexOf(arr,item){for(var i = 0;i<arr.length;i++){if(arr[i] == item){console.log(i);}}}indexOf(["a","b","c"],"b");//用數組元素組成字符串function arrStr(arr){var arr2 = arr.join();console.log(arr2)}arrStr(["a","b"]);//刪除數組最后一個元素function removeArrEndItem(){arr = ["a","b","c"];var arr2 = arr.pop();console.log(arr);//在原數組上操作
console.log(arr2);//刪除的元素
}removeArrEndItem();//在數組末尾添加新元素function addEndItem(){var arr = ["a","b","c"];var arr2 = arr.push();console.log(arr);//在原數組上操作
console.log(arr2);//數組arr的長度
}addEndItem();//數組排序function sort(){var arr = ["c","b","a"];arr.sort();console.log(arr);var points = [40,100,1,5,25,10];points.sort(function(a,b){return a-b});console.log(points);var points01 = [40,100,1,5,25,10];points01.sort(function(a,b){return b-a});console.log(points01);}sort();//將數組元素轉換為字符串輸出function str(){var fruits = ["Banana", "Orange", "Apple", "Mango"];var str = fruits.toString();console.log(str);}str();</script></body>
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?運行結果：
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轉載于:https://www.cnblogs.com/flower-qh/p/9354931.html
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