join 数组转字符串，指定间隔符

var list =[ 'a' , 'b' , 'c' , 'd' ]

var str = list .join( "," )

console .log( str ) //a,b,c,d

pop 数组删除删除最后一个元素,返回删除的元素

var list =[ 'a' , 'b' , 'c' , 'd' ]

var p = list .pop()

console .log( p ) //d

console .log( list ) //['a','b','c']

shift 从数组中删除第一个元素,返回删除的元素

var s = list .shift()

console .log( s ) //a

console .log( list ) //['b','c']

push 数组结尾添加元素并返回新数组的长度

var list =[ 'a' , 'b' , 'c' ]

var i = list .push( 'd' );

console .log( i ); //4

console .log( list ) //['a','b','c','d']

unshift 数组开头添加元素并返回新数组的长度

var j = list .unshift( 'x' )

console .log( j ); //5

console .log( list ) //['x','a','b','c','d']

splice(x,y) 第一个参数添加新元素的位置、第二个参数删除多少个元素

var list =[ 'a' , 'b' , 'c' ]

//splice 向数组添加新元素

var a = list .splice( 2 , 0 , "m" , "n" );

console .log( list ) //['a','b','m','n','c']

//splice 删除元素

var list =[ 'a' , 'b' , 'c' ]

var a = list .splice( 0 , 1 )

console .log( a ); //['a']

console .log( list ) //['b','c']

concat 合并数组

var list1 = [ 'a' , 'b' ]

var list2 = [ 'm' , 'n' ]

var newList = list1 .concat( list2 )

console .log( list1 ) //['a','b']

console .log( newList ) //['a','b','m','n']

slice 裁剪数组,返回新数组，它不会从原数组中删除任何元素

var list = [ 'a' , 'b' , 'c' ]

var newList = list .slice( 1 )

console .log( newList ) //['b','c']

console .log( list ) //['a','b','c']

var newList = list .slice( 1 , 2 )

console .log( newList ) //['b']

console .log( list ) //['a','b','c']

sort 排序，改变原数组

var points = [ 40 , 100 , 5 , 25 ];

points .sort( function ( a , b ){ return a - b });

console .log( points ) //[5,25,40,100]

reverse 反转数组

points .reverse()

console .log( points ) //[100,40,25,5]

forEach 数组遍历

var list =[ 1 , 2 , 3 , 4 , 5 ]

list .forEach( item => {

console .log( item )

})

filter 数组过滤 ,不改变原数组，返回新数组

var nums = [ 45 , 4 , 9 , 16 , 25 ];

var over10 = nums .filter( item => item > 10 )

console .log( nums ) //[45, 4, 9, 16, 25]

console .log( over10 ) //[45, 16, 25]

some 检查某些数组值是否满足条件 返回true,false

var nums = [ 45 , 4 , 9 , 16 , 25 ];

var over10 = nums .some( item => item > 10 )

console .log( over10 ) //true

indexOf 在数组中搜索元素值并返回其位置,没有返回-1

var nums = [ 45 , 4 , 9 , 16 , 25 ]

var idx = nums .indexOf( 9 )

console .log( idx ) //2

var idx = nums .indexOf( 10 )

console .log( idx ) //-1

find 返回满足条件的第一个数组元素的值,没有返回undefined

var nums = [ 45 , 4 , 9 , 56 , 25 ]

var mum = nums .find( item => item > 50 )

console .log( mum ) //56

findIndex 返回满足条件的第一个数组元素的索引，没有返回-1

var nums = [ 45 , 4 , 9 , 56 , 25 ]

var mum = nums .findIndex( item => item > 10 )

console .log( mum ) //0