let last = array.at(-1) 0x02 如果浏览器还不支持这个方法,可以Polyfill: function at(n) { // ToInteger() abstract op n = Math.trunc(n) || 0; // Allow negative indexing from the end if (n < 0) n += this.length; // OOB access is guaranteed to return undefined if (n < 0 |...
Array.prototype上的新的新方法 ---at 函数,可以让我们更加方便的访问到数组 和 字符串末尾的元素。 在实际开发中,我经常需要去访问到数组或者是字符串中末尾的某个元素的。 但是吧,通常使用的法子不是很好的,比如my_array[my_array.length - N]。 或者是 使用可能没有什么性能的操作,比如my_array.slice(-N...
Many languages allownegative bracket indexinglike [-1] to access elements from the end of an object / array / string. This is not possible in JavaScript, because [] is used for accessing both arrays and objects. obj[-1] refers to the value of key -1, not to the last property of the...
for-loop部分(这里,我使用Array.prototype.reduce来累积最终的robot状态)可以保留下来,用于迭代字符串中的每个指令并计算robot的新状态。 IMO通过将状态转换逻辑放在一个单独的对象中,当/如果您希望您的机器人支持新的指令,它可以使重构变得更容易。 function robotSimulator(param) { if (param.length === 0 || ...
[i];},set:function(value){array[i]=value;},});// Fancy negative slice indexing to count back from the end.Object.defineProperty(wrappedArray,'-'+i.toString(), {get:function(){returnarray[array.length-i];},set:function(value){array[array.length-i]=value;},});})(i);}return...
Or by indexing an array with a variable whose contents don't in any way represent a number--like typing myArray['bonobo monkey'] = 27. You'll get no complaints, because rather than adding an index to the array, you're adding a property. Speaking of which... We can add properties ...
数据类型:数字(1、3.14、0xFF,用isNaN函数测试一个值不是数字);布尔(true、false);字符串('hello'、"OK"、'and "nested" ',16位unicode字符集);对象(var o = new Object()、var o={x:1, y:2, z:3}、o.x=1、o["x"]=1);数组(var a = new Array()、var a = new Array(1,2,3)、va...
array.dimension Returns the dimension of the array. Slicing Given a view, we can change the indexing by shifting, truncating or permuting the strides. This lets us perform operations like array reversals or matrix transpose inconstant time(well, technicallyO(shape.length), but since shape.length...
数据阵列由大多数Dataview API返回,这些API可以返回多个结果,例如dv.pages()。您也可以使用dv.array(<array>)显式地将普通JavaScript数组转换为Dataview数组。如果要将Data数组转换回普通数组,请使用DataArray#array()。 Indexing and Swizzling 索引和混合
The array initially contains no elements, even though it might have a non-zero length. If the value specified is not a number, an array of length 1 is created, with the first element having the specified value.The following code creates an array of length 25, then assigns values to the...