diff --git a/staging/javascript/src/utils.js b/staging/javascript/src/utils.js
new file mode 100644
index 0000000..9bcbfa6
--- /dev/null
+++ b/staging/javascript/src/utils.js
@@ -0,0 +1,51 @@
+/**
+ *   MIT License
+ *
+ *   Copyright (c) 2021 Guilherme Tadashi Maeoka
+ *   https://github.com/guimspace/envelope-matrix
+ *
+ *   Permission is hereby granted, free of charge, to any person obtaining a copy
+ *   of this software and associated documentation files (the "Software"), to deal
+ *   in the Software without restriction, including without limitation the rights
+ *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *   copies of the Software, and to permit persons to whom the Software is
+ *   furnished to do so, subject to the following conditions:
+ *
+ *   The above copyright notice and this permission notice shall be included in
+ *   all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *   SOFTWARE.
+ */
+
+module.exports = {
+  initEnvelope, getElement
+}
+
+function getElement (envelope, i, j) {
+  if (i === j) return envelope.diagg[i]
+  else if (envelope.enveCol[j] === envelope.enveCol[j + 1]) return 0
+
+  let p = envelope.enveCol[j]
+  const l = envelope.enveLin[p]
+
+  if (l > i) return 0
+
+  p = p + i - l
+
+  return envelope.enve[p]
+}
+
+function initEnvelope () {
+  return {
+    diagg: [],
+    enve: [],
+    enveCol: [],
+    enveLin: []
+  }
+}
diff --git a/staging/javascript/src/wrap.js b/staging/javascript/src/wrap.js
new file mode 100644
index 0000000..423e658
--- /dev/null
+++ b/staging/javascript/src/wrap.js
@@ -0,0 +1,93 @@
+/**
+ *   MIT License
+ *
+ *   Copyright (c) 2021 Guilherme Tadashi Maeoka
+ *   https://github.com/guimspace/envelope-matrix
+ *
+ *   Permission is hereby granted, free of charge, to any person obtaining a copy
+ *   of this software and associated documentation files (the "Software"), to deal
+ *   in the Software without restriction, including without limitation the rights
+ *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *   copies of the Software, and to permit persons to whom the Software is
+ *   furnished to do so, subject to the following conditions:
+ *
+ *   The above copyright notice and this permission notice shall be included in
+ *   all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *   SOFTWARE.
+ */
+
+module.exports = {
+  generateEnvelope, unwrapEnvelope
+}
+
+function unwrapEnvelope (envelope, matrix, isLine = false) {
+  const n = envelope.diagg.length
+
+  let p = 0
+
+  for (let i = 0; i < n; i++) {
+    matrix[i][i] = envelope.diagg[i]
+
+    const d = envelope.enveLin[i] - p
+    const top = envelope.enveCol[i + 1]
+
+    while (p < top) {
+      if (isLine) matrix[i][d + p] = envelope.enve[p]
+      else matrix[d + p][i] = envelope.enve[p]
+
+      p++
+    }
+  }
+}
+
+function generateEnvelope (matrix, isLine = false) {
+  const diagg = []
+  const enve = []
+  const enveCol = []
+  const enveLin = []
+
+  const n = matrix.length
+
+  let p = 0
+  let j = 0
+
+  while (j < n) {
+    diagg[j] = matrix[j][j]
+
+    let i = 0
+    if (isLine) {
+      while (i < j && matrix[j][i] === 0) { i++ }
+    } else {
+      while (i < j && matrix[i][j] === 0) { i++ }
+    }
+
+    enveCol[j] = p
+    enveLin[j] = i
+
+    p += j - i
+
+    while (i < j) {
+      isLine ? enve.push(matrix[j][i]) : enve.push(matrix[i][j])
+      i++
+    }
+
+    j++
+  }
+
+  enve.push(null)
+  enveCol[j] = p
+
+  return {
+    diagg: diagg,
+    enve: enve,
+    enveCol: enveCol,
+    enveLin: enveLin
+  }
+}
diff --git a/staging/javascript/test/test.js b/staging/javascript/test/test.js
new file mode 100644
index 0000000..99b7e77
--- /dev/null
+++ b/staging/javascript/test/test.js
@@ -0,0 +1,22 @@
+const wrap = require('../src/wrap.js')
+
+const matrix = [
+  [11, 12, 0, 14, 0, 0],
+  [-12, 22, 23, 0, 0, 0],
+  [0, -23, 33, 0, 0, 0],
+  [-14, 0, 0, 44, 0, 46],
+  [0, 0, 0, 0, 55, 0],
+  [0, 0, 0, -46, 0, 66]
+]
+const n = matrix.length
+
+const envelope = wrap.generateEnvelope(matrix)
+console.log(envelope)
+
+const regen = new Array(n)
+for (let i = 0; i < n; i++) {
+  regen[i] = new Array(n).fill(0)
+}
+
+wrap.unwrapEnvelope(envelope, regen)
+console.log(regen)