Ensure _.flatten handles empty arrays.

dist/lodash.compat.js

@@ -1112,7 +1112,8 @@
       while (++index < length) {
         var value = array[index];
 
-        if (value && typeof value == 'object' && value.length && (isArray(value) || isArguments(value))) {
+        if (value && typeof value == 'object' && typeof value.length == 'number'
+            && (isArray(value) || isArguments(value))) {
           // recursively flatten arrays (susceptible to call stack limits)
           if (!isShallow) {
             value = baseFlatten(value, isShallow, isArgArrays);

dist/lodash.compat.min.js

@@ -8,7 +8,7 @@
 }function f(n){return typeof n.toString!="function"&&typeof(n+"")=="string"}function c(){}function p(n){n.length=0,y.length<j&&y.push(n)}function s(n){var t=n.k;t&&s(t),n.b=n.k=n.l=n.object=n.number=n.string=n.n=null,m.length<j&&m.push(n)}function g(n,t,e){t||(t=0),typeof e=="undefined"&&(e=n?n.length:0);var r=-1;e=e-t||0;for(var u=Array(0>e?0:e);++r<e;)u[r]=n[t+r];return u}function h(e){function y(n){return n&&typeof n=="object"&&!qe(n)&&ve.call(n,"__wrapped__")?n:new m(n)}function m(n,t){this.__chain__=!!t,this.__wrapped__=n
 }function j(n,t,e,r,u){var o=n;if(e){if(o=e(o),typeof o!="undefined")return o;o=n}var a=mt(o);if(a){var l=we.call(o);if(!U[l]||!Le.nodeClass&&f(o))return o;var c=qe(o)}if(!a||!t)return a?c?g(o):Ye({},o):o;switch(a=$e[l],l){case T:case q:return new a(+o);case G:case H:return new a(o);case M:return a(o.source,A.exec(o))}l=!r,r||(r=i()),u||(u=i());for(var s=r.length;s--;)if(r[s]==n)return u[s];return o=c?a(o.length):{},c&&(ve.call(n,"index")&&(o.index=n.index),ve.call(n,"input")&&(o.input=n.input)),r.push(n),u.push(o),(c?Xe:tr)(n,function(n,a){o[a]=j(n,t,e,r,u)
 }),l&&(p(r),p(u)),o}function Q(n,t,e){if(typeof n!="function")return Gt;if(typeof t=="undefined")return n;var r=n.__bindData__||Le.o&&!n.name;if(typeof r=="undefined"){var u=P&&ge.call(n);Le.o||!u||I.test(u)||(r=!0),(Le.o||!r)&&(r=!P||P.test(u),Te(n,r))}if(true!==r&&r&&1&r[1])return n;switch(e){case 1:return function(e){return n.call(t,e)};case 2:return function(e,r){return n.call(t,e,r)};case 3:return function(e,r,u){return n.call(t,e,r,u)};case 4:return function(e,r,u,o){return n.call(t,e,r,u,o)}
-}return qt(n,t)}function Y(n,t,e,r){r=(r||0)-1;for(var u=n?n.length:0,o=[];++r<u;){var a=n[r];if(a&&typeof a=="object"&&a.length&&(qe(a)||st(a))){t||(a=Y(a,t,e));var i=-1,l=a.length,f=o.length;for(o.length+=l;++i<l;)o[f++]=a[i]}else e||o.push(a)}return o}function nt(n,t,e,r,u,o){if(e){var a=e(n,t);if(typeof a!="undefined")return!!a}if(n===t)return 0!==n||1/n==1/t;if(n===n&&!(n&&V[typeof n]||t&&V[typeof t]))return!1;if(null==n||null==t)return n===t;var l=we.call(n),c=we.call(t);if(l==z&&(l=J),c==z&&(c=J),l!=c)return!1;
+}return qt(n,t)}function Y(n,t,e,r){r=(r||0)-1;for(var u=n?n.length:0,o=[];++r<u;){var a=n[r];if(a&&typeof a=="object"&&typeof a.length=="number"&&(qe(a)||st(a))){t||(a=Y(a,t,e));var i=-1,l=a.length,f=o.length;for(o.length+=l;++i<l;)o[f++]=a[i]}else e||o.push(a)}return o}function nt(n,t,e,r,u,o){if(e){var a=e(n,t);if(typeof a!="undefined")return!!a}if(n===t)return 0!==n||1/n==1/t;if(n===n&&!(n&&V[typeof n]||t&&V[typeof t]))return!1;if(null==n||null==t)return n===t;var l=we.call(n),c=we.call(t);if(l==z&&(l=J),c==z&&(c=J),l!=c)return!1;
 switch(l){case T:case q:return+n==+t;case G:return n!=+n?t!=+t:0==n?1/n==1/t:n==+t;case M:case H:return n==ee(t)}if(c=l==L,!c){if(ve.call(n,"__wrapped__")||ve.call(t,"__wrapped__"))return nt(n.__wrapped__||n,t.__wrapped__||t,e,r,u,o);if(l!=J||!Le.nodeClass&&(f(n)||f(t)))return!1;var l=!Le.argsObject&&st(n)?ne:n.constructor,s=!Le.argsObject&&st(t)?ne:t.constructor;if(l!=s&&!(yt(l)&&l instanceof l&&yt(s)&&s instanceof s))return!1}for(s=!u,u||(u=i()),o||(o=i()),l=u.length;l--;)if(u[l]==n)return o[l]==t;
 var g=0,a=!0;if(u.push(n),o.push(t),c){if(l=n.length,g=t.length,a=g==n.length,!a&&!r)return a;for(;g--;)if(c=l,s=t[g],r)for(;c--&&!(a=nt(n[c],s,e,r,u,o)););else if(!(a=nt(n[g],s,e,r,u,o)))break;return a}return nr(t,function(t,i,l){return ve.call(l,i)?(g++,a=ve.call(n,i)&&nt(n[i],t,e,r,u,o)):void 0}),a&&!r&&nr(n,function(n,t,e){return ve.call(e,t)?a=-1<--g:void 0}),s&&(p(u),p(o)),a}function et(n,t,e,r,u){(qe(t)?Ct:tr)(t,function(t,o){var a,i,l=t,f=n[o];if(t&&((i=qe(t))||er(t))){for(l=r.length;l--;)if(a=r[l]==t){f=u[l];
 break}if(!a){var c;e&&(l=e(f,t),c=typeof l!="undefined")&&(f=l),c||(f=i?qe(f)?f:[]:er(f)?f:{}),r.push(t),u.push(f),c||et(f,t,e,r,u)}}else e&&(l=e(f,t),typeof l=="undefined"&&(l=t)),typeof l!="undefined"&&(f=l);n[o]=f})}function rt(e,r,u){var a=-1,l=ft(),f=e?e.length:0,c=[],g=!r&&f>=w&&l===n,h=u||g?i():c;if(g){var v=o(h);v?(l=t,h=v):(g=!1,h=u?h:(p(h),c))}for(;++a<f;){var v=e[a],y=u?u(v,a,e):v;(r?!a||h[h.length-1]!==y:0>l(h,y))&&((u||g)&&h.push(y),c.push(v))}return g?(p(h.b),s(h)):u&&p(h),c}function ut(n){return function(t,e,r){var u={};

dist/lodash.js

@@ -843,7 +843,8 @@
       while (++index < length) {
         var value = array[index];
 
-        if (value && typeof value == 'object' && value.length && (isArray(value) || isArguments(value))) {
+        if (value && typeof value == 'object' && typeof value.length == 'number'
+            && (isArray(value) || isArguments(value))) {
           // recursively flatten arrays (susceptible to call stack limits)
           if (!isShallow) {
             value = baseFlatten(value, isShallow, isArgArrays);

dist/lodash.min.js

@@ -10,8 +10,8 @@ for(var r=-1,u=M[typeof n]&&qe(n),o=u?u.length:0;++r<o&&(e=u[r],false!==t(n[e],e
 if(!u)return o;var a=arguments,i=0,f=typeof e=="number"?2:a.length;if(3<f&&"function"==typeof a[f-2])var l=nt(a[--f-1],a[f--],2);else 2<f&&"function"==typeof a[f-1]&&(l=a[--f]);for(;++i<f;)if((u=a[i])&&M[typeof u])for(var c=-1,p=M[typeof u]&&qe(u),s=p?p.length:0;++c<s;)r=p[c],o[r]=l?l(o[r],u[r]):u[r];return o}function J(n){var t,e=[];if(!n||!M[typeof n])return e;for(t in n)ve.call(n,t)&&e.push(t);return e}function X(n){return n&&typeof n=="object"&&!ze(n)&&ve.call(n,"__wrapped__")?n:new Y(n)}function Y(n,t){this.__chain__=!!t,this.__wrapped__=n
 }function Z(n,t,e,r,u){var o=n;if(e){if(o=e(o),typeof o!="undefined")return o;o=n}var a=yt(o);if(a){var f=_e.call(o);if(!L[f])return o;var l=ze(o)}if(!a||!t)return a?l?s(o):G({},o):o;switch(a=De[f],f){case F:case T:return new a(+o);case q:case K:return new a(o);case P:return a(o.source,O.exec(o))}f=!r,r||(r=i()),u||(u=i());for(var p=r.length;p--;)if(r[p]==n)return u[p];return o=l?a(o.length):{},l&&(ve.call(n,"index")&&(o.index=n.index),ve.call(n,"input")&&(o.input=n.input)),r.push(n),u.push(o),(l?xt:y)(n,function(n,a){o[a]=Z(n,t,e,r,u)
 }),f&&(c(r),c(u)),o}function nt(n,t,e){if(typeof n!="function")return Mt;if(typeof t=="undefined")return n;var r=n.__bindData__||Fe.a&&!n.name;if(typeof r=="undefined"){var u=A&&pe.call(n);Fe.a||!u||N.test(u)||(r=!0),(Fe.a||!r)&&(r=!A||A.test(u),Te(n,r))}if(true!==r&&r&&1&r[1])return n;switch(e){case 1:return function(e){return n.call(t,e)};case 2:return function(e,r){return n.call(t,e,r)};case 3:return function(e,r,u){return n.call(t,e,r,u)};case 4:return function(e,r,u,o){return n.call(t,e,r,u,o)
-}}return Pt(n,t)}function tt(n,t,e,r){r=(r||0)-1;for(var u=n?n.length:0,o=[];++r<u;){var a=n[r];if(a&&typeof a=="object"&&a.length&&(ze(a)||pt(a))){t||(a=tt(a,t,e));var i=-1,f=a.length,l=o.length;for(o.length+=f;++i<f;)o[l++]=a[i]}else e||o.push(a)}return o}function et(n,t,e,r,u,o){if(e){var a=e(n,t);if(typeof a!="undefined")return!!a}if(n===t)return 0!==n||1/n==1/t;if(n===n&&!(n&&M[typeof n]||t&&M[typeof t]))return!1;if(null==n||null==t)return n===t;var f=_e.call(n),l=_e.call(t);if(f==$&&(f=W),l==$&&(l=W),f!=l)return!1;
-switch(f){case F:case T:return+n==+t;case q:return n!=+n?t!=+t:0==n?1/n==1/t:n==+t;case P:case K:return n==ee(t)}if(l=f==D,!l){if(ve.call(n,"__wrapped__")||ve.call(t,"__wrapped__"))return et(n.__wrapped__||n,t.__wrapped__||t,e,r,u,o);if(f!=W)return!1;var f=n.constructor,p=t.constructor;if(f!=p&&!(gt(f)&&f instanceof f&&gt(p)&&p instanceof p))return!1}for(p=!u,u||(u=i()),o||(o=i()),f=u.length;f--;)if(u[f]==n)return o[f]==t;var s=0,a=!0;if(u.push(n),o.push(t),l){if(f=n.length,s=t.length,a=s==n.length,!a&&!r)return a;
+}}return Pt(n,t)}function tt(n,t,e,r){r=(r||0)-1;for(var u=n?n.length:0,o=[];++r<u;){var a=n[r];if(a&&typeof a=="object"&&typeof a.length=="number"&&(ze(a)||pt(a))){t||(a=tt(a,t,e));var i=-1,f=a.length,l=o.length;for(o.length+=f;++i<f;)o[l++]=a[i]}else e||o.push(a)}return o}function et(n,t,e,r,u,o){if(e){var a=e(n,t);if(typeof a!="undefined")return!!a}if(n===t)return 0!==n||1/n==1/t;if(n===n&&!(n&&M[typeof n]||t&&M[typeof t]))return!1;if(null==n||null==t)return n===t;var f=_e.call(n),l=_e.call(t);
+if(f==$&&(f=W),l==$&&(l=W),f!=l)return!1;switch(f){case F:case T:return+n==+t;case q:return n!=+n?t!=+t:0==n?1/n==1/t:n==+t;case P:case K:return n==ee(t)}if(l=f==D,!l){if(ve.call(n,"__wrapped__")||ve.call(t,"__wrapped__"))return et(n.__wrapped__||n,t.__wrapped__||t,e,r,u,o);if(f!=W)return!1;var f=n.constructor,p=t.constructor;if(f!=p&&!(gt(f)&&f instanceof f&&gt(p)&&p instanceof p))return!1}for(p=!u,u||(u=i()),o||(o=i()),f=u.length;f--;)if(u[f]==n)return o[f]==t;var s=0,a=!0;if(u.push(n),o.push(t),l){if(f=n.length,s=t.length,a=s==n.length,!a&&!r)return a;
 for(;s--;)if(l=f,p=t[s],r)for(;l--&&!(a=et(n[l],p,e,r,u,o)););else if(!(a=et(n[s],p,e,r,u,o)))break;return a}return d(t,function(t,i,f){return ve.call(f,i)?(s++,a=ve.call(n,i)&&et(n[i],t,e,r,u,o)):void 0}),a&&!r&&d(n,function(n,t,e){return ve.call(e,t)?a=-1<--s:void 0}),p&&(c(u),c(o)),a}function rt(n,t,e,r,u){(ze(t)?xt:y)(t,function(t,o){var a,i,f=t,l=n[o];if(t&&((i=ze(t))||g(t))){for(f=r.length;f--;)if(a=r[f]==t){l=u[f];break}if(!a){var c;e&&(f=e(l,t),c=typeof f!="undefined")&&(l=f),c||(l=i?ze(l)?l:[]:g(l)?l:{}),r.push(t),u.push(l),c||rt(l,t,e,r,u)
 }}else e&&(f=e(l,t),typeof f=="undefined"&&(f=t)),typeof f!="undefined"&&(l=f);n[o]=l})}function ut(e,r,u){var a=-1,f=ft(),l=e?e.length:0,s=[],v=!r&&l>=_&&f===n,h=u||v?i():s;if(v){var g=o(h);g?(f=t,h=g):(v=!1,h=u?h:(c(h),s))}for(;++a<l;){var g=e[a],y=u?u(g,a,e):g;(r?!a||h[h.length-1]!==y:0>f(h,y))&&((u||v)&&h.push(y),s.push(g))}return v?(c(h.b),p(h)):u&&c(h),s}function ot(n){return function(t,e,r){var u={};e=X.createCallback(e,r,3),r=-1;var o=t?t.length:0;if(typeof o=="number")for(;++r<o;){var a=t[r];
 n(u,a,e(a,r,t),t)}else y(t,function(t,r,o){n(u,t,e(t,r,o),o)});return u}}function at(n,t,e,r,u,o){var a=1&t,i=2&t,f=4&t,l=8&t,c=16&t,p=32&t,s=n;if(!i&&!gt(n))throw new re;c&&!e.length&&(t&=-17,c=e=!1),p&&!r.length&&(t&=-33,p=r=!1);var v=n&&n.__bindData__;if(v)return!a||1&v[1]||(v[4]=u),!a&&1&v[1]&&(t|=8),!f||4&v[1]||(v[5]=o),c&&ge.apply(v[2]||(v[2]=[]),e),p&&ge.apply(v[3]||(v[3]=[]),r),v[1]|=t,at.apply(null,v);if(!a||i||f||p||!(Fe.fastBind||je&&c))g=function(){var v=arguments,h=a?u:this;return(f||c||p)&&(v=Re.call(v),c&&de.apply(v,e),p&&ge.apply(v,r),f&&v.length<o)?(t|=16,at(n,l?t:-4&t,v,null,u,o)):(i&&(n=h[s]),this instanceof g?(h=yt(n.prototype)?ke(n.prototype):{},v=n.apply(h,v),yt(v)?v:h):n.apply(h,v))

dist/lodash.underscore.js

@@ -419,7 +419,8 @@
     while (++index < length) {
       var value = array[index];
 
-      if (value && typeof value == 'object' && value.length && (isArray(value) || isArguments(value))) {
+      if (value && typeof value == 'object' && typeof value.length == 'number'
+          && (isArray(value) || isArguments(value))) {
         // recursively flatten arrays (susceptible to call stack limits)
         if (!isShallow) {
           value = baseFlatten(value, isShallow, isArgArrays);

dist/lodash.underscore.min.js

@@ -4,7 +4,7 @@
  * Build: `lodash underscore exports="amd,commonjs,global,node" -o ./dist/lodash.underscore.js`
  */
 ;(function(){function n(n,r,t){t=(t||0)-1;for(var e=n?n.length:0;++t<e;)if(n[t]===r)return t;return-1}function r(n,r){var t=n.l,e=r.l;if(t!==e){if(t>e||typeof t=="undefined")return 1;if(t<e||typeof e=="undefined")return-1}return n.m-r.m}function t(n){return"\\"+vr[n]}function e(){}function u(n){return n instanceof u?n:new o(n)}function o(n,r){this.__chain__=!!r,this.__wrapped__=n}function i(n,r,t){if(typeof n!="function")return Q;if(typeof r=="undefined")return n;switch(t){case 1:return function(t){return n.call(r,t)
-};case 2:return function(t,e){return n.call(r,t,e)};case 3:return function(t,e,u){return n.call(r,t,e,u)};case 4:return function(t,e,u,o){return n.call(r,t,e,u,o)}}return J(n,r)}function f(n,r,t,e){e=(e||0)-1;for(var u=n?n.length:0,o=[];++e<u;){var i=n[e];if(i&&typeof i=="object"&&i.length&&(Pr(i)||y(i))){r||(i=f(i,r,t));var a=-1,l=i.length,c=o.length;for(o.length+=l;++a<l;)o[c++]=i[a]}else t||o.push(i)}return o}function a(n,r,t,e){if(n===r)return 0!==n||1/n==1/r;if(n===n&&!(n&&hr[typeof n]||r&&hr[typeof r]))return!1;
+};case 2:return function(t,e){return n.call(r,t,e)};case 3:return function(t,e,u){return n.call(r,t,e,u)};case 4:return function(t,e,u,o){return n.call(r,t,e,u,o)}}return J(n,r)}function f(n,r,t,e){e=(e||0)-1;for(var u=n?n.length:0,o=[];++e<u;){var i=n[e];if(i&&typeof i=="object"&&typeof i.length=="number"&&(Pr(i)||y(i))){r||(i=f(i,r,t));var a=-1,l=i.length,c=o.length;for(o.length+=l;++a<l;)o[c++]=i[a]}else t||o.push(i)}return o}function a(n,r,t,e){if(n===r)return 0!==n||1/n==1/r;if(n===n&&!(n&&hr[typeof n]||r&&hr[typeof r]))return!1;
 if(null==n||null==r)return n===r;var o=Or.call(n),i=Or.call(r);if(o!=i)return!1;switch(o){case fr:case ar:return+n==+r;case lr:return n!=+n?r!=+r:0==n?1/n==1/r:n==+r;case pr:case sr:return n==r+""}if(i=o==ir,!i){if(Ar.call(n,"__wrapped__")||r instanceof u)return a(n.__wrapped__||n,r.__wrapped__||r,t,e);if(o!=cr)return!1;var o=n.constructor,f=r.constructor;if(o!=f&&!(j(o)&&o instanceof o&&j(f)&&f instanceof f))return!1}for(t||(t=[]),e||(e=[]),o=t.length;o--;)if(t[o]==n)return e[o]==r;var l=!0,c=0;
 if(t.push(n),e.push(r),i){if(c=r.length,l=c==n.length)for(;c--&&(l=a(n[c],r[c],t,e)););return l}return Lr(r,function(r,u,o){return Ar.call(o,u)?(c++,!(l=Ar.call(n,u)&&a(n[u],r,t,e))&&rr):void 0}),l&&Lr(n,function(n,r,t){return Ar.call(t,r)?!(l=-1<--c)&&rr:void 0}),l}function l(n,r,t){for(var e=-1,u=v(),o=n?n.length:0,i=[],f=t?[]:i;++e<o;){var a=n[e],l=t?t(a,e,n):a;(r?!e||f[f.length-1]!==l:0>u(f,l))&&(t&&f.push(l),i.push(a))}return i}function c(n){return function(r,t,e){var u={};t=K(t,e,3),e=-1;var o=r?r.length:0;
 if(typeof o=="number")for(;++e<o;){var i=r[e];n(u,i,t(i,e,r),r)}else Qr(r,function(r,e,o){n(u,r,t(r,e,o),o)});return u}}function p(n,r,t,e,u,o){var i=1&r,f=2&r,a=4&r,l=8&r,c=16&r,h=32&r,v=n;if(!f&&!j(n))throw new TypeError;if(c&&!t.length&&(r&=-17,c=t=!1),h&&!e.length&&(r&=-33,h=e=!1),!i||f||a||h||!(Cr.fastBind||Br&&c))y=function(){var g=arguments,m=i?u:this;return(a||c||h)&&(g=Ir.call(g),c&&Sr.apply(g,t),h&&Tr.apply(g,e),a&&g.length<o)?(r|=16,p(n,l?r:-4&r,g,null,u,o)):(f&&(n=m[v]),this instanceof y?(m=s(n.prototype),g=n.apply(m,g),x(g)?g:m):n.apply(m,g))

lodash.js

@@ -1131,7 +1131,8 @@
       while (++index < length) {
         var value = array[index];
 
-        if (value && typeof value == 'object' && value.length && (isArray(value) || isArguments(value))) {
+        if (value && typeof value == 'object' && typeof value.length == 'number'
+            && (isArray(value) || isArguments(value))) {
           // recursively flatten arrays (susceptible to call stack limits)
           if (!isShallow) {
             value = baseFlatten(value, isShallow, isArgArrays);

test/test.js

@@ -1336,6 +1336,11 @@
         ok(pass);
       }
     });
+
+    test('should work with empty arrays', function() {
+      var actual = _.flatten([[], [[]], [[], [[[]]]]]);
+      deepEqual(actual, []);
+    });
   }(1, 2, 3));
 
   /*--------------------------------------------------------------------------*/