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【已解决】js中如何合并两个数组且支持空数组合并

JS crifan 730浏览 0评论
js list merge
JavaScript Array concat() Method
How to merge two arrays in JavaScript and de-duplicate items – Stack Overflow
How to merge array of arrays in one array (in JavaScript)? – Stack Overflow
javascript – Merge two array of objects based on a key – Stack Overflow
结果用:
        var authorsIllustrators = []
        var bookAuthors = curBookDict["author"]["bookAuthors"]
        console.log("bookAuthors=", bookAuthors)
        if (bookAuthors) {
            authorsIllustrators.concat(bookAuthors)
        }
        console.log("authorsIllustrators=", authorsIllustrators)
        var illustrators = curBookDict["author"]["illustrators"]
        console.log("illustrators=", illustrators)
        if (illustrators) {
            authorsIllustrators.concat(illustrators)
        }
        console.log("authorsIllustrators=", authorsIllustrators)
        var authorsIllustratorsStr = listToStr(authorsIllustrators)
        console.log("authorsIllustratorsStr=", authorsIllustratorsStr)
输出:
book_detail.js:130 bookAuthors= ["Audrey Wood"]
11:22:30.957 book_detail.js:134 authorsIllustrators= []
11:22:30.958 book_detail.js:136 illustrators= []
11:22:30.959 book_detail.js:140 authorsIllustrators= []
11:22:30.960 book_common.js:24 listToStr: listValue=[]
11:22:30.961 book_detail.js:142 authorsIllustratorsStr= 
竟然第一次空数组contact一个有值的数组,结果是空
-》看来是不支持空数组
改为:
        var authorsIllustrators = []
        var bookAuthors = curBookDict["author"]["bookAuthors"]
        console.log("bookAuthors=", bookAuthors)
        if (bookAuthors) {
            authorsIllustrators = bookAuthors
        }
        console.log("authorsIllustrators=", authorsIllustrators)
        var illustrators = curBookDict["author"]["illustrators"]
        console.log("illustrators=", illustrators)
        if (illustrators) {
            if (authorsIllustrators) {
                authorsIllustrators = illustrators
            } else {
                authorsIllustrators.concat(illustrators)
            }
        }
        console.log("authorsIllustrators=", authorsIllustrators)
        var authorsIllustratorsStr = listToStr(authorsIllustrators)
        console.log("authorsIllustratorsStr=", authorsIllustratorsStr)
竟然也不对:
bookAuthors= ["Audrey Wood"]
11:25:25.080 book_detail.js:134 authorsIllustrators= ["Audrey Wood"]
11:25:25.081 book_detail.js:136 illustrators= []
11:25:25.082 book_detail.js:144 authorsIllustrators= []
js merge empty list
Concat in an empty array in Javascript – Stack Overflow
jquery – Javascript Array Concat not working. Why? – Stack Overflow
后来改为:
authorsIllustrators = authorsIllustrators.concat(bookAuthors)
authorsIllustrators = authorsIllustrators.concat(illustrators)
即可:
bookAuthors= ["Audrey Wood"]
11:29:51.980 book_detail.js:132 illustrators= []
11:29:51.982 book_detail.js:150 authorsIllustrators= ["Audrey Wood"]
【总结】
此处用:
var authorsIllustrators = []
authorsIllustrators = authorsIllustrators.concat(bookAuthors)
authorsIllustrators = authorsIllustrators.concat(illustrators)
即可实现数组合并,且也支持其中任意一个数组为空
而前面之所以:
        if (bookAuthors) {
            authorsIllustrators.concat(bookAuthors)
        }
出错,是因为:
忘了把合并后的数组返回给原先的变量。。。。

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