数组相关方法
concat 用来连接多个数组
<script>
var a = [1,2,3];
var b = [3,4,5];
var c = a.concat(b);
console.log(c); // [1,2,3,3,4,5,]
</script>
join 把数组元素拿出来，根据指定的符号连接成一个字符串
<script>
var a = [1,2,3];
var b = a.join('|');
console.log(b); // 1|2|3
</script>
pop 删除数组的最后一个元素
<script>
var a = [1,2,3];
var b = a.pop();
console.log(a); // [1, 2]
console.log(b); //2
</script>
push 在数组的末尾添加一个元素
<script>
var a = [1,2,3];
a.push("python");
console.log(a); // [1, 2, 3, "python"]
</script>
revrse 反转数组
<script>
var a = [1,2,3];
console.log(a.reverse()); //[3, 2, 1]
</script>
splice 可以添加或者删除元素
<script>
//splice只有1个参数时，表示从数组这个位置开始删除到最后
var a1 = [1,2,3, 'python', 'java' ];
console.log(a1.splice(1)); //[2, 3, "python", "java"]
console.log(a1); //[1]
//如果是两个参数，第1个参数表示从哪个位置开始删除，第二个删除几个
var a2 = [1,2,3, 'python', 'java' ];
console.log(a2.splice(1, 0)); //[] 我这里设置的0所以1个都没有删除
console.log(a2); //[1,2,3, 'python', 'java' ]
// 从索引位置2开始删除1个
var a3 = [1,2,3, 'python', 'java' ];
console.log(a3.splice(2, 1)); //[3]
console.log(a3); //[1, 2, "python", "java"]
//如果超过2个参数，则后的参数添加
var a4 = [1,2,3, 'python', 'java'];
console.log(a4.splice(2, 1, 'c++', 99)); //[3]
console.log(a4); //[1, 2, "c++", 99, "python", "java"]
</script>