将参数传递给javascript中的map、filter、sort函数答案

【问题标题】：passing argument to map, filter, sort function in javascript将参数传递给javascript中的map、filter、sort函数
【发布时间】：2020-06-16 15:37:51
【问题描述】：

我在尝试在 sort(callback) 函数中传递 Value(sortBy ) 时遇到错误。

 let sortBy = 'birth'
    	let usersJSON = [
    	{
    		name: "Sania Mirza",
    		birth: "11/30/2011"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/1999"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/2020 "
    	}
]

   
    usersJSON.sort(function (a, b) {
    	//var dateA = new Date(a.birth), dateB = new Date(b.birth); // this is working fine 
    	var dateA = new Date(a.sortBy), dateB = new Date(b.sortBy); // I want sorting based on "sortBy"  
    	return dateA - dateB;
    });
    console.log("componentDidMount :", JSON.stringify(usersJSON, null, ' '))

【问题讨论】：

标签： javascript object key

【解决方案1】：

应该是 a[sortBy] 。这与点表示法相同，除了 sortBy 可能来自变量，而当您执行 a.sortyBy 时，它会查找键 sortyBy（字符串），而不是动态变量，因此您会收到错误消息。

let sortBy = 'birth'
    	let usersJSON = [
    	{
    		name: "Sania Mirza",
    		birth: "11/30/2011"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/1999"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/2020 "
    	}
]

   
    usersJSON.sort(function (a, b) {
    	//var dateA = new Date(a.birth), dateB = new Date(b.birth); // this is working file 
    	var dateA = new Date(a[sortBy]), dateB = new Date(b[sortBy]); // I want sorting based on "sortBy"  
    	return dateA - dateB;
    });
    console.log(usersJSON)

【讨论】：

【解决方案2】：

 let sortBy = 'birth'
    	let usersJSON = [
    	{
    		name: "Sania Mirza",
    		birth: "11/30/2011"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/1999"
    	}, {
    		name: "Lata Pathak",
    		birth: "10/31/2020 "
    	}
]

   
    usersJSON.sort(function (a, b) {
    	//var dateA = new Date(a.birth), dateB = new Date(b.birth); // this is working file 
    	var dateA = new Date(a[sortBy]), dateB = new Date(b[sortBy]); // I want sorting based on "sortBy"  
    	return dateA - dateB;
    });
    console.log("componentDidMount :", JSON.stringify(usersJSON, null, ' '))

【讨论】：