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;
});