答案1
Use a sequential for loop:
var myStringArray = ["Hello","World"]; var arrayLength = myStringArray.length; for (var i = 0; i < arrayLength; i++) { alert(myStringArray[i]); //Do something }@zipcodeman suggests the use of the for...in statement, but for iterating arrays for-in should be avoided, that statement is meant to enumerate object properties.
It shouldn't be used for array-like objects because:
- The order of iteration is not guaranteed, the array indexes may not be visited in numeric order.
- Inherited properties are also enumerated.
The second point is that it can give you a lot of problems, for example, if you extend the Array.prototype object to include a method there, that property will be also enumerated.
For example:
Array.prototype.foo = "foo!"; var array = ['a', 'b', 'c']; for (var i in array) { alert(array[i]); }The above code will alert, "a", "b", "c" and "foo!".
That be particularly a problem if you use some library that relies heavily on native prototypes augmention (such as MooTools for example).
The for-in statement as I said before is there to enumerate object properties, for example:
var obj = { "a": 1, "b": 2, "c": 3 }; for (var prop in obj) { if (obj.hasOwnProperty(prop)) { // or if (Object.prototype.hasOwnProperty.call(obj,prop)) for safety... alert("prop: " + prop + " value: " + obj[prop]) } }In the above example the hasOwnProperty method allows you to enumerate only own properties, that's it, only the properties that the object physically has, no inherited properties.
I would recommend you to read the following article:
答案2
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map
The map() method creates a new array with the results of calling a provided function on every element in the calling array.
arr = ["table", "chair"]; // solution arr.map((e) => { console.log(e); return e; });