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JavaScript .isArray Implementations
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| // Attempt #1: using typeof | |
| // fails in all cases since typeof [] returns "object" | |
| Array.prototype.isArray = function(obj) { | |
| return (typeof obj === "array"); | |
| } | |
| // Attempt #2: using instanceof | |
| // fails when obj = Array.prototype | |
| // and when array is defined in another window or frame | |
| Array.prototype.isArray = function(obj) { | |
| return (obj instanceof Array); | |
| } | |
| // Attempt #3: using object prototype.toString | |
| // this works and is the actual ECMAScript 5.1 implementation | |
| Array.prototype.isArray = function(obj) { | |
| return Object.prototype.toString.call(obj) == "[object Array]"; | |
| } | |
| // Attempt #4: using duck typing | |
| // this works for the most part but is easily fooled | |
| Array.prototype.isArray = function(obj) { | |
| if (typeof arg === 'object' && | |
| ('join' in arg && typeof arg.join === 'function') && | |
| ('length' in arg && typeof arg.length === 'number')) { | |
| return true; | |
| } | |
| return false; | |
| } |
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