Structure of Wasm bindings (#13)

* create js folder

* structure of js package

js/.gitignore

@@ -0,0 +1,9 @@
+/target
+**/*.rs.bk
+bin/
+pkg/
+wasm-pack.log
+.pnp.cjs
+.pnp.loader.mjs
+docs_build/
+.yarn

js/.travis.yml

@@ -0,0 +1,69 @@
+language: rust
+sudo: false
+
+cache: cargo
+
+matrix:
+  include:
+
+  # Builds with wasm-pack.
+  - rust: beta
+    env: RUST_BACKTRACE=1
+    addons:
+      firefox: latest
+      chrome: stable
+    before_script:
+      - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
+      - (test -x $HOME/.cargo/bin/cargo-generate || cargo install --vers "^0.2" cargo-generate)
+      - cargo install-update -a
+      - curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh -s -- -f
+    script:
+      - cargo generate --git . --name testing
+      # Having a broken Cargo.toml (in that it has curlies in fields) anywhere
+      # in any of our parent dirs is problematic.
+      - mv Cargo.toml Cargo.toml.tmpl
+      - cd testing
+      - wasm-pack build
+      - wasm-pack test --chrome --firefox --headless
+
+  # Builds on nightly.
+  - rust: nightly
+    env: RUST_BACKTRACE=1
+    before_script:
+      - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
+      - (test -x $HOME/.cargo/bin/cargo-generate || cargo install --vers "^0.2" cargo-generate)
+      - cargo install-update -a
+      - rustup target add wasm32-unknown-unknown
+    script:
+      - cargo generate --git . --name testing
+      - mv Cargo.toml Cargo.toml.tmpl
+      - cd testing
+      - cargo check
+      - cargo check --target wasm32-unknown-unknown
+      - cargo check                                 --no-default-features
+      - cargo check --target wasm32-unknown-unknown --no-default-features
+      - cargo check                                 --no-default-features --features console_error_panic_hook
+      - cargo check --target wasm32-unknown-unknown --no-default-features --features console_error_panic_hook
+      - cargo check                                 --no-default-features --features "console_error_panic_hook wee_alloc"
+      - cargo check --target wasm32-unknown-unknown --no-default-features --features "console_error_panic_hook wee_alloc"
+
+  # Builds on beta.
+  - rust: beta
+    env: RUST_BACKTRACE=1
+    before_script:
+      - (test -x $HOME/.cargo/bin/cargo-install-update || cargo install cargo-update)
+      - (test -x $HOME/.cargo/bin/cargo-generate || cargo install --vers "^0.2" cargo-generate)
+      - cargo install-update -a
+      - rustup target add wasm32-unknown-unknown
+    script:
+      - cargo generate --git . --name testing
+      - mv Cargo.toml Cargo.toml.tmpl
+      - cd testing
+      - cargo check
+      - cargo check --target wasm32-unknown-unknown
+      - cargo check                                 --no-default-features
+      - cargo check --target wasm32-unknown-unknown --no-default-features
+      - cargo check                                 --no-default-features --features console_error_panic_hook
+      - cargo check --target wasm32-unknown-unknown --no-default-features --features console_error_panic_hook
+      # Note: no enabling the `wee_alloc` feature here because it requires
+      # nightly for now.