JS array sorting

The sort() method of arrays in JavaScript is mainly used to sort the elements of the array. Among them, the sort() method has an optional parameter. However, this parameter must be a function. When calling the sort() method of an array, if no parameters are passed, the elements in the array will be sorted in alphabetical order (character encoding order). If you want to sort according to other criteria, you need to pass a parameter. Is a function that compares two values ​​and returns a number that describes the relative order of the two values.

1. Sort the numerical array from small to large.

var arr = [22,12,3,43,56,47,4];
arr.sort();
console.log(arr); // [12, 22, 3, 4, 43, 47, 56]，按照数字的第一个字排序的arr.sort(function (m, n) {
 if (m < n) return -1  //m < n 返回-1是从小到大排序，返回1是从大到小排序
 else if (m > n) return 1
 else return 0});
console.log(arr); // [3, 4, 12, 22, 43, 47, 56]，按照数值大小排序

2. Perform a case-insensitive alphabetical sort on a string array

var arr = ['abc', 'Def', 'BoC', 'FED'];
console.log(arr.sort()); // ["BoC", "Def", "FED", "abc"]，按首个字母在ASIIC中出现的位置排序console.log(arr.sort(function(s, t){
 var a = s.toLowerCase(); var b = t.toLowerCase(); if (a < b) return -1;//从小到大排序
 if (a > b) return 1; return 0;
})); // ["abc", "BoC", "Def", "FED"]

3. Sort an array containing objects, requiring descending order based on age in the object Sequential arrangement

var arr = [{'name': '张三', age: 26},{'name': '李四', age: 12},{'name': '王五', age: 37},{'name': '赵六', age: 4}];var objectArraySort = function (keyName) {
 return function (objectN, objectM) {
  var valueN = objectN[keyName]  var valueM = objectM[keyName]  if (valueN < valueM) return 1 //从大到小排序
  else if (valueN > valueM) return -1
  else return 0
 }
}
arr.sort(objectArraySort(&#39;age&#39;))
console.log(arr) // [{&#39;name&#39;: &#39;王五&#39;, age: 37},{&#39;name&#39;: &#39;张三&#39;, age: 26},{&#39;name&#39;: &#39;李四&#39;, age: 12},{&#39;name&#39;: &#39;赵六&#39;, age: 4}]

             

The sort() method of arrays in JavaScript is mainly used to sort the elements of the array. Among them, the sort() method has an optional parameter. However, this parameter must be a function. When calling the sort() method of an array, if no parameters are passed, the elements in the array will be sorted in alphabetical order (character encoding order). If you want to sort according to other criteria, you need to pass a parameter. Is a function that compares two values ​​and returns a number that describes the relative order of the two values.

1. Sort the numerical array from small to large.

var arr = [22,12,3,43,56,47,4];
arr.sort();
console.log(arr); // [12, 22, 3, 4, 43, 47, 56]，按照数字的第一个字排序的arr.sort(function (m, n) {
 if (m < n) return -1  //m < n 返回-1是从小到大排序，返回1是从大到小排序
 else if (m > n) return 1
 else return 0});
console.log(arr); // [3, 4, 12, 22, 43, 47, 56]，按照数值大小排序

2. Perform a case-insensitive alphabetical sort on a string array

var arr = ['abc', 'Def', 'BoC', 'FED'];
console.log(arr.sort()); // ["BoC", "Def", "FED", "abc"]，按首个字母在ASIIC中出现的位置排序console.log(arr.sort(function(s, t){
 var a = s.toLowerCase(); var b = t.toLowerCase(); if (a < b) return -1;//从小到大排序
 if (a > b) return 1; return 0;
})); // ["abc", "BoC", "Def", "FED"]

3. Sort an array containing objects, requiring descending order based on age in the object Arrange in order

var arr = [{'name': '张三', age: 26},{'name': '李四', age: 12},{'name': '王五', age: 37},{'name': '赵六', age: 4}];var objectArraySort = function (keyName) {
 return function (objectN, objectM) {
  var valueN = objectN[keyName]  var valueM = objectM[keyName]  if (valueN < valueM) return 1 //从大到小排序
  else if (valueN > valueM) return -1
  else return 0
 }
}
arr.sort(objectArraySort(&#39;age&#39;))
console.log(arr) // [{&#39;name&#39;: &#39;王五&#39;, age: 37},{&#39;name&#39;: &#39;张三&#39;, age: 26},{&#39;name&#39;: &#39;李四&#39;, age: 12},{&#39;name&#39;: &#39;赵六&#39;, age: 4}]

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