Math.max.apply(Math,my_array); Math.min.apply(Math,my_array);
它在Firefox和IE上工作得很好,但在Chrome上,我总是收到最大调用堆栈大小超过错误…我当前的数组有221954个元素,这不是我最大的.
有人知道如何在Chrome上解决这个错误吗?如何优化最大和最小值的搜索?
对于那些不敢相信的人,请在Chrome的控制台中尝试:
var xxx = [] for(var i=0; i<300000; i++){ xxx.push(Math.random()); } Math.max.apply(Math,xxx);
—> RangeError:超过最大调用堆栈大小
解决方法
Function.prototype.apply只能接收有限长度的数组作为其第二个参数.
在本地,我使用以下方式在Chrome中进行了测试:
function limit(l) { var x = []; x.length = l; (function (){}).apply(null,x); }
在本地,限制(l)精确地与l = 124980崩溃.在金丝雀,这是另一个数字,但也〜125k.
这是为什么会发生这种情况的一个例子说明:https://code.google.com/p/v8/issues/detail?id=2896(在其他JS引擎中也是可以重用的,例如MDN提到的问题:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply#Using_apply_and_built-in_functions(从“但请注意…”),指出WebKit中的这个问题bugzilla:https://bugs.webkit.org/show_bug.cgi?id=80797).据我所知,为什么RangeError在V8中抛出:
V8在汇编中实现了Function.prototype.apply.在调用该函数之前,它应该放置所有函数调用参数,例如thisArg,以及第二个arg数组的所有成员,一个一个地到栈上,然后再调用javascript函数.但堆栈的容量有限,如果你达到极限,你将得到RangeError.
这是我在V8源码(IA-32 assembly,builtins-ia32.cc)中找到的:
void Builtins::Generate_FunctionApply(MacroAssembler* masm) { static const int kArgumentsOffset = 2 * kPointerSize; static const int kReceiverOffset = 3 * kPointerSize; static const int kFunctionOffset = 4 * kPointerSize; { FrameScope frame_scope(masm,StackFrame::INTERNAL); __ push(Operand(ebp,kFunctionOffset)); // push this __ push(Operand(ebp,kArgumentsOffset)); // push arguments __ InvokeBuiltin(Builtins::APPLY_PREPARE,CALL_FUNCTION); // Check the stack for overflow. We are not trying to catch // interruptions (e.g. debug break and preemption) here,so the "real stack // limit" is checked. Label okay; ExternalReference real_stack_limit = ExternalReference::address_of_real_stack_limit(masm->isolate()); __ mov(edi,Operand::StaticVariable(real_stack_limit)); // Make ecx the space we have left. The stack might already be overflowed // here which will cause ecx to become negative. // !! ADDED COMMENT: IA-32 stack grows downwards,if address to its current top is 0 then it cannot be placed any more elements into. esp is the pointer to stack top. __ mov(ecx,esp); // !! ADDED COMMENT: edi holds the "real_stack_limit",which holds the minimum address that stack should not grow beyond. If we subtract edi from ecx (=esp,or,in other words,"how much space is left on the stack"),we may get a negative value,and the comment above says that __ sub(ecx,edi); // Make edx the space we need for the array when it is unrolled onto the // stack. // !! ADDED COMMENT: eax holds the number of arguments for this apply call,where every member of the 2nd argument array counts as separate argument __ mov(edx,eax); // !! ADDED COMMENT: kPointerSizeLog2 - kSmiTagSize is the base-2-logarithm of how much space would 1 argument take. By shl we in fact get 2^(kPointerSizeLog2 - kSmiTagSize) * arguments_count,i.e. how much space do actual arguments occupy __ shl(edx,kPointerSizeLog2 - kSmiTagSize); // Check if the arguments will overflow the stack. // !! ADDED COMMENT: we compare ecx which is how much data we can put onto stack with edx which now means how much data we need to put onto stack __ cmp(ecx,edx); __ j(greater,&okay); // Signed comparison. // Out of stack space. __ push(Operand(ebp,4 * kPointerSize)); // push this __ push(eax); __ InvokeBuiltin(Builtins::APPLY_OVERFLOW,CALL_FUNCTION);
而这是APPLY_OVERFLOW函数,用JS编写(再次,V8源,runtime.js):
function APPLY_OVERFLOW(length) { throw %MakeRangeError('stack_overflow',[]); }
编辑:在你的情况下,我会像:
var max = -Infinity; for(var i = 0; i < arr.length; i++ ) if (arr[i] > max) max = arr[i];