在写文章的某些时候，并不希望读者一下子就看到接下来的内容，先藏起来。比如，我们提了一个问题，希望读者脑海里先闪过思考的瞬间。这时候可以考虑把答案部分先折叠起来。真好，Rmarkdown是有这个功能的，虽然是借助HTML下实现的。
很简单，借助details 属性就可以了：
<details>
<summary>Toggle answer</summary>
# ```{r mes}
message("You can try sUmmary : ")
summary(cars)
# ```
</details>
结果如下
可以看到折叠区于不折叠的markdown语法并无二致，均是可以执行的。需要主要的是折叠区不要放标题##，默认标题是不折叠的。
<script>
document.addEventListener("click", function (event) {
if (event.target.classList.contains("aaron-collapse")) {
event.target.classList.toggle("active");
var content = event.target.nextElementSibling;
if (content.style.display === "block") {
content.style.display = "none";
} else {
content.style.display = "block";
}
}
})
</script>
<style>
.aaron-collapse {
background-color: #eee;
color: #444;
cursor: pointer;
padding: 18px;
width: 100%;
border: none;
text-align: left;
outline: none;
font-size: 15px;
}
.aaron-content {
padding: 0 18px;
display: none;
overflow: hidden;
background-color: #f1f1f1;
}
</style>
<button class="aaron-collapse">View session info</button>
<div class="aaron-content">
\\\```
R version 4.0.0 Patched (2020-05-01 r78341)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.4 LTS
Matrix products: default
BLAS: /home/luna/Software/R/R-4-0-branch-dev/lib/libRblas.so
LAPACK: /home/luna/Software/R/R-4-0-branch-dev/lib/libRlapack.so
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] parallel stats4 stats graphics grDevices utils datasets
[8] methods base
other attached packages:
[1] scater_1.17.3 ggplot2_3.3.2
[3] AnnotationHub_2.21.1 BiocFileCache_1.13.0
[5] dbplyr_1.4.4 SingleR_1.3.6
[7] celldex_0.99.1 ensembldb_2.13.1
[9] AnnotationFilter_1.13.0 GenomicFeatures_1.41.0
[11] AnnotationDbi_1.51.1 scRNAseq_2.3.6
[13] SingleCellExperiment_1.11.6 SummarizedExperiment_1.19.5
[15] DelayedArray_0.15.6 matrixStats_0.56.0
[17] Matrix_1.2-18 Biobase_2.49.0
[19] GenomicRanges_1.41.5 GenomeInfoDb_1.25.5
[21] IRanges_2.23.10 S4Vectors_0.27.12
[23] BiocGenerics_0.35.4 BiocStyle_2.17.0
[25] rebook_0.99.0
loaded via a namespace (and not attached):
[1] ggbeeswarm_0.6.0 colorspace_1.4-1
[3] ellipsis_0.3.1 scuttle_0.99.10
[5] XVector_0.29.3 BiocNeighbors_1.7.0
[7] bit64_0.9-7 interactiveDisplayBase_1.27.5
[9] codetools_0.2-16 knitr_1.29
[11] Rsamtools_2.5.3 graph_1.67.1
[13] shiny_1.5.0 BiocManager_1.30.10
[15] compiler_4.0.0 httr_1.4.1
[17] assertthat_0.2.1 fastmap_1.0.1
[19] lazyeval_0.2.2 later_1.1.0.1
[21] BiocSingular_1.5.0 htmltools_0.5.0
[23] prettyunits_1.1.1 tools_4.0.0
[25] rsvd_1.0.3 gtable_0.3.0
[27] glue_1.4.1 GenomeInfoDbData_1.2.3
[29] dplyr_1.0.0 rappdirs_0.3.1
[31] Rcpp_1.0.4.6 vctrs_0.3.1
[33] Biostrings_2.57.2 ExperimentHub_1.15.0
[35] rtracklayer_1.49.3 DelayedMatrixStats_1.11.1
[37] xfun_0.15 stringr_1.4.0
[39] ps_1.3.3 mime_0.9
[41] lifecycle_0.2.0 irlba_2.3.3
[43] XML_3.99-0.3 zlibbioc_1.35.0
[45] scales_1.1.1 hms_0.5.3
[47] promises_1.1.1 ProtGenerics_1.21.0
[49] yaml_2.2.1 curl_4.3
[51] memoise_1.1.0 gridExtra_2.3
[53] biomaRt_2.45.1 stringi_1.4.6
[55] RSQLite_2.2.0 BiocVersion_3.12.0
[57] BiocParallel_1.23.0 rlang_0.4.6
[59] pkgconfig_2.0.3 bitops_1.0-6
[61] evaluate_0.14 lattice_0.20-41
[63] purrr_0.3.4 GenomicAlignments_1.25.3
[65] CodeDepends_0.6.5 bit_1.1-15.2
[67] processx_3.4.2 tidyselect_1.1.0
[69] magrittr_1.5 bookdown_0.20
[71] R6_2.4.1 generics_0.0.2
[73] DBI_1.1.0 pillar_1.4.4
[75] withr_2.2.0 RCurl_1.98-1.2
[77] tibble_3.0.1 crayon_1.3.4
[79] rmarkdown_2.3 viridis_0.5.1
[81] progress_1.2.2 grid_4.0.0
[83] blob_1.2.1 callr_3.4.3
[85] digest_0.6.25 xtable_1.8-4
[87] httpuv_1.5.4 openssl_1.4.2
[89] munsell_0.5.0 viridisLite_0.3.0
[91] beeswarm_0.2.3 vipor_0.4.5
[93] askpass_1.1
\\\```
</div>
参考：
