【已解决】js中如何合并两个数组且支持空数组合并

js list merge

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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