javascript - Why does slice not work directly on arguments? -

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• how slice “arguments” 4 answers

tested out on fiddle after looking @ underscore.

this seems hack call slice on arguments when not on prototype chain.

why not on prototype chain when works on arguments.

var slice = array.prototype.slice; function test () {     return slice.call(arguments,1);     // return arguments.slice(1) } var foo = test(1,2,3,4); _.each(foo, function(val){     console.log(val) }); 

>>> object.prototype.tostring.call(arguments) <<< "[object arguments]" >>> array.isarray(arguments) //is not array <<< false >>> arguments instanceof array //does not inherit array prototype either <<< false 

arguments not array object, is, not inherit array prototype. however, contains array-like structure (numeric keys , length property), array.prototype.slice can applied it. called duck typing.

oh , of course, array.prototype.slice returns array, hence can used convert array-like objects / collections new array. ^{(ref: mdn array slice method - array-like objects)}