From d6f5c9c8b5fa5866785faefb9c91c277580dc0b9 Mon Sep 17 00:00:00 2001
From: Ivan Zverev <ivan.zverev.ext@siemens.com>
Date: Mon, 27 May 2019 17:41:12 +0300
Subject: [PATCH] [New] `parse`: add `allowSparse` option for not collapsing
 arrays with missing indices

Fixes #181.
---
 lib/parse.js   | 6 ++++++
 test/.eslintrc | 1 +
 test/parse.js  | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/lib/parse.js b/lib/parse.js
index 057adc85..5f697c1c 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -7,6 +7,7 @@ var has = Object.prototype.hasOwnProperty;
 var defaults = {
     allowDots: false,
     allowPrototypes: false,
+    allowSparse: false,
     arrayLimit: 20,
     charset: 'utf-8',
     charsetSentinel: false,
@@ -203,6 +204,7 @@ var normalizeParseOptions = function normalizeParseOptions(opts) {
     return {
         allowDots: typeof opts.allowDots === 'undefined' ? defaults.allowDots : !!opts.allowDots,
         allowPrototypes: typeof opts.allowPrototypes === 'boolean' ? opts.allowPrototypes : defaults.allowPrototypes,
+        allowSparse: typeof opts.allowSparse === 'boolean' ? opts.allowSparse : defaults.allowSparse,
         arrayLimit: typeof opts.arrayLimit === 'number' ? opts.arrayLimit : defaults.arrayLimit,
         charset: charset,
         charsetSentinel: typeof opts.charsetSentinel === 'boolean' ? opts.charsetSentinel : defaults.charsetSentinel,
@@ -239,5 +241,9 @@ module.exports = function (str, opts) {
         obj = utils.merge(obj, newObj, options);
     }
 
+    if (options.allowSparse === true) {
+        return obj;
+    }
+
     return utils.compact(obj);
 };
diff --git a/test/.eslintrc b/test/.eslintrc
index f76d573c..4879a61a 100644
--- a/test/.eslintrc
+++ b/test/.eslintrc
@@ -11,6 +11,7 @@
         "no-buffer-constructor": 0,
         "no-extend-native": 0,
         "no-magic-numbers": 0,
+        "no-sparse-arrays": 0,
         "object-curly-newline": 0,
         "sort-keys": 0
     }
diff --git a/test/parse.js b/test/parse.js
index 397b867d..790bf572 100644
--- a/test/parse.js
+++ b/test/parse.js
@@ -237,6 +237,14 @@ test('parse()', function (t) {
         st.end();
     });
 
+    t.test('parses sparse arrays', function (st) {
+        st.deepEqual(qs.parse('a[4]=1&a[1]=2', { allowSparse: true }), { a: [, '2', , , '1'] });
+        st.deepEqual(qs.parse('a[1][b][2][c]=1', { allowSparse: true }), { a: [, { b: [, , { c: '1' }] }] });
+        st.deepEqual(qs.parse('a[1][2][3][c]=1', { allowSparse: true }), { a: [, [, , [, , , { c: '1' }]]] });
+        st.deepEqual(qs.parse('a[1][2][3][c][1]=1', { allowSparse: true }), { a: [, [, , [, , , { c: [, '1'] }]]] });
+        st.end();
+    });
+
     t.test('parses semi-parsed strings', function (st) {
         st.deepEqual(qs.parse({ 'a[b]': 'c' }), { a: { b: 'c' } });
         st.deepEqual(qs.parse({ 'a[b]': 'c', 'a[d]': 'e' }), { a: { b: 'c', d: 'e' } });