Javascript:forEach在内置数组上经常失败

我经常想做这样的事情：

["string1", "string2"].forEach(function(str) { 
    // Handle string
})

这似乎偶尔奏效，但通常（至少是Chrome）会抛出错误

Cannot read property 'forEach' of undefined

为什么我的就地数组“未定义”

相比之下，这将按预期工作：

var myStrings = ["string1", "string2"]
myStrings.forEach(function(str) {
    // Handle string
})

有什么好处

编辑

代码示例：

// This works:
var methods = {}
,   methodNames = ["move", "x", "y", "cx", "cy", "opacity", "attr", "fill", "stroke", "front", "after", "back", "dx", "dmove", "dy", "remove"]

methodNames.forEach(function(method) {
    methods[method] = { value: function() { return this.mainGroup[method].apply(this.mainGroup, arguments) }}
})

// This throws "Cannot read property 'forEach' of undefined
methods = {}
["move", "x", "y", "cx", "cy", "opacity", "attr", "fill", "stroke", "front", "after", "back", "dx", "dmove", "dy", "remove"].forEach(function(method) {
    methods[method] = { value: function() { return this.mainGroup[method].apply(this.mainGroup, arguments) }}
})

---

“methods={}”旁边缺少分号会导致错误

// This throws "Cannot read property 'forEach' of undefined
methods = {};  // <-- HERE
["move", "x", "y", "cx", "cy", "opacity", "attr", "fill", "stroke", "front", "after", "back", "dx", "dmove", "dy", "remove"].forEach(function(method) {
    methods[method] = { value: function() { return this.mainGroup[method].apply(this.mainGroup, arguments); }}
});

---

虽然没有必要，但作为一种良好的做法，我建议在适当的时候使用分号。

无法复制，forEach在chrome中对我来说很好。请提供一个示例代码。@Mr_Pouet-提供的代码示例。谢谢！但是为什么呢？为什么{}[]本身无效？

var a = {};
a['a', 'b'] = 1;  // a = {'a':1 , 'b':1}