JavaScript 数组处理方法总结

缺乏、安全感 2021-09-11 08:08 487阅读 0赞

数组处理方法

//定义数组
         var array = [];
         undefined
         //查看类型
         typeof(array);
         "object"
         //往数组里添加数据
         array = ['first','second','third']
         ["first", "second", "third"]
         //数组长度
         array.length
         3
         //索引
         array[0]
         "first"
         //添加数组新内容
         array[3] = 'fourth'
         "fourth"
         array
         ["first", "second", "third", "fourth"]
         //使用push添加数组的新数据，是往数组后添加数据
         array.push('fifth','sixth')
         6
         array
         ["first", "second", "third", "fourth", "fifth", "sixth"]
         //往前添加是使用unshift-------------------
         var newArray = ["second", "three", "four", "one", "two"]
         newArray.unshift('haha')
         6
         newArray
         ["haha", "second", "three", "four", "one", "two"]
         //-----------------------
         //删除数据最后一个元素使用pop
         array.pop()
         "sixth"
         array
         ["first", "second", "third", "fourth", "fifth"]
         ///删除数组第一个元素使用shift
         array.shift()
         "first"
         ///删除数组中某一个元素的值会使用delete，不会删除数组中该元素
         delete array[3]
         true
         
         array
         ["second", "third", "fourth", undefined × 1]
         //彻底删除数组里的元素使用splice方法
         array.splice(3)
         [undefined × 1]
         array
         ["second", "third", "fourth"]
         //合并两个数组使用concat
         var array2 = ['one','two']
         undefined
         var newArray = array.concat(array2)
         undefined
         newArray
         ["second", "third", "fourth", "one", "two"]