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JavaScript中的多维数组用法指南

编程语言IT知识数据结构数组前端开发多维数组

多维数组未直接在JavaScript中提供。如果要使用任何充当多维数组的东西, 则需要使用另一个一维数组来创建多维数组。因此, JavaScript中的多维数组被称为另一个数组中的数组。我们需要将一些数组放入一个数组中, 然后整个事情就像多维数组一样工作。其他数组将插入其中的数组, 该数组在我们的代码中用作多维数组。定义多维数组与定义普通一维数组完全相同。
一维数组：

var arr = []; // Empty 1D arrayvar arr1 = ["A", "B", "C", "D"] // 1D array contains some alphabetsvar arr1 = [1, 2, 3, 4, 5] // 1D array contains some digits

多维数组：
方法1：
1st, need to define some 1D arrayvar arr1 = ["ABC", 24, 18000]; var arr2 = ["EFG", 30, 30000]; var arr3 = ["IJK", 28, 41000]; var arr4 = ["EFG", 31, 28000]; var arr5 = ["EFG", 29, 35000]; // "salary" defines like a 1D array but it already contains some 1D arrayvar salary = [arr1, arr2, arr3, arr4, arr5];

这里arr1, arr2, …arr5是里面的一些一维数组薪水数组。
方法2：
var salary = [["ABC", 24, 18000], ["EFG", 30, 30000], ["IJK", 28, 41000], ["EFG", 31, 28000], ];

这里, 薪水数组的工作方式类似于多维数组。这种表示法称为数组文字。
访问薪水数组的元素：
  • 要访问数组元素, 我们需要一个基于索引的简单表示法
    // This notation access the salary of "ABC" person which is 18000, // [0] selects 1st row, and [2] selects the 3rd element// of that 1st row which is 18000salary[0][2]; // Similarly, salary[3][2]; // Selects 28000**This notation is used for both Method 1 and Method 2.

  • 对于许多迭代, 我们需要使用循环来访问元素,
    // This loop is for outer arrayfor (var i = 0, l1 = salary.length; i < l1; i++) {// This loop is for inner-arraysfor (var j = 0, l2 = salary[i].length; j < l2; j++) {// Accessing each elements of inner-arraydocuments.write( salary[i][j] ); }}

在多维数组中添加元素：多维数组中的元素添加可以通过以下两种方式实现：内部数组or外层阵列。内部数组可以通过两种不同的方式完成。
  • 向内部数组添加元素：
    • 我们可以使用简单方括号在多维数组中添加元素的符号。
      salary[3][3] = "India"; // It adds "India" at the 4th index of 4th sub-array, // If we print the entire 4th sub-array, document.write(salary[3]); // the output will be :["EFG", 31, 28000, "India"]// indexing starts from 0

    • 我们可以用推()在数组中添加元素的方法。
      salary[3].push("India", "Mumbai"); // It add "India" at the 4th index and "Mumbai" at// 5th index of 4th sub-array// If we print the entire 4th sub-array, // document.write(salary[3]); // The output will be :["EFG", 31, 28000, "India", "Mumbai"]// Indexing starts from 0

  • 向外部数组添加元素：它与以前的方法非常相似。
    salary.push(["MNO", 29, 33300]); // This row added after the last row in the "salary" array

删除多维数组中的元素：我们可以用pop()从内部数组中删除元素的方法, 也可以使用pop()删除整个内部数组的方法。
// Remove last element from 4th sub-array// That is 28000 indexing starts from 0salary[3].pop(); // Removes last sub-array// That is "["EFG", 31, 28000]"salary.pop();

【JavaScript中的多维数组用法指南】范例1：
// Prints a simple multidimensional array in JavaScript < script> var arr1 = [ "ABC" , 24, 18000]; var arr2 = [ "EFG" , 30, 30000]; var arr3 = [ "IJK" , 28, 41000]; var arr4 = [ "EFG" , 31, 28000]; var arr5 = [ "EFG" , 29, 35000]; var salary = [arr1, arr2, arr3, arr4, arr5]; for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); } < /script>

输出如下：
ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000EFG, 29, 35000

范例2：
// Prints a simple multidimensional array in // JavaScript with different declaration < script> var salary = [ [ "ABC" , 24, 18000], [ "EFG" , 30, 30000], [ "IJK" , 28, 41000], [ "EFG" , 31, 28000], ]; for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); } < /script>

输出如下：
ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000EFG, 29, 35000

范例3：
// Prints a simple multidimensional array in JavaScript // where we just print the salary of a specific person < script> var salary = [ [ "ABC" , 24, 18000], [ "EFG" , 30, 30000], [ "IJK" , 28, 41000], [ "EFG" , 31, 28000], ]; document.write( "salary of 2nd person : " + salary[1][2] + "< br> " ); document.write( "salary of 4th person : " + salary[3][2] + "< br> " ); < /script>

输出如下：
salary of 2nd person : 30000salary of 4th person : 28000

范例4：
// Prints a simple multidimensional array in // JavaScript where we add elements in the array // using simple square bracket and push() method < script> var salary = [ [ "ABC" , 24, 18000], [ "EFG" , 30, 30000], [ "IJK" , 28, 41000], [ "EFG" , 31, 28000], ]; // Prints first array document.write( "Original array :< br> " ); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); }// Adding "India" at the 4th index of 4th sub array salary[3][3] = "India" ; document.write( "< br> after adding \"India\" at the 4th array :< br> " ); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); }document.write( "< br> after adding \"USA\" and \"Canada\" " + "at the 3rd array using \"push()\" method :< br> " ); salary[2].push( "USA" , "Canada" ); // Adding "USA" and "Canada" in the 2nd sub-array for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); } < /script>

输出如下：
Original array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000after adding "India" at the 4th array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000, Indiaafter adding "USA" and "Canada" at the 3rd array using "push()" method :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000, USA, CanadaEFG, 31, 28000, India

范例5：
// Prints a simple multidimensional array in // JavaScript where we add a new inner array < script> var salary = [ [ "ABC" , 24, 18000], [ "EFG" , 30, 30000], [ "IJK" , 28, 41000], [ "EFG" , 31, 28000], ]; // Prints first array document.write( "Original array :< br> " ); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); }document.write( "< br> After adding a new inner array :< br> " ); // Pushing a new sub-array salary.push([ "MNO" , 29, 33300]); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); } < /script>

输出如下：
Original array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000After adding a new inner array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000MNO, 29, 33300

范例6：
// Prints a simple multidimensional array in // JavaScript where we remove a single element //and a entire sub-array < script> var salary = [ [ "ABC" , 24, 18000], [ "EFG" , 30, 30000], [ "IJK" , 28, 41000], [ "EFG" , 31, 28000], ]; // Prints first array document.write( "Original array :< br> " ); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); }document.write( "< br> After removing last element " + "of last inner array :< br> " ); // Removes the last element of 3rd sub-array salary[3].pop(); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); }document.write( "< br> After removing last inner array :< br> " ); // Removes last sub-array salary.pop(); for ( var i = 0; i < salary.length; i++) { document.write(salary[i] + "< br> " ); } < /script>

输出如下：
Original array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31, 28000After removing last element of last inner array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000EFG, 31After removing last inner array :ABC, 24, 18000EFG, 30, 30000IJK, 28, 41000

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