数组去重和splice() 方法split()跟join()数组方法pop() push() unshift() shift()
2016-11-08 16:45
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数组去重
var arr=['1','2','2','5','3','10','3','10','20','21'];
var a=[];
function array(arr){
for(var i=0;i<arr.length;i++){
if(a.indexOf(arr[i])<0){//在a数组中找不到相同的数时,把arr数组的值插入a数组中。
a.push(arr[i])
}
}
return a;
}
array(arr)
console.log(a)
splice() 方法用于插入、删除或替换数组的元素。
array.splice(index,howmany,item1,.....,itemX)
index 必需。规定从何处添加/删除元素。
该参数是开始插入和(或)删除的数组元素的下标,必须是数字。
howmany必需。规定应该删除多少元素。必须是数字,但可以是 "0"。
如果未规定此参数,则删除从 index 开始到原数组结尾的所有元素。
item1, ..., itemX 可选。要添加到数组的新元素
var arr=["appendChild","removeChild","replaceChild","insertBefore"]
arr.splice(2,0,"haha")
console.log(arr)
第二个填0的话添加进数组
打印["appendChild", "removeChild", "haha", "replaceChild", "insertBefore"]
第二个填1的话添加进数组,然后在这个位置删除一个数。相当于把它替换了。
打印["appendChild",
"removeChild", "haha", "insertBefore"]
第二个填1的话添加进数组,第三个不填就会删除。
打印["appendChild", "removeChild", "insertBefore"]
split()切割成数组的形式
var arr="hello do you know how many?"
var news=arr.split(" ")
console.log(news)
打印的是["hello", "do", "you", "know", "how", "many?"]
join()转换成字符串
var arr=['split','match'];
console.log(avar arr=["hello", "do", "you", "know", "how", "many?"];
arr.push("news")
console.log(arr)rr.join('-'))
没有添加 '-' 的是split,match
打印的是 split-match
push()尾部添加 pop()尾部删除 unshift()头部添加 shift()头部删除
pop()删除数组的最后一个元素。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.pop()
console.log(arr)
打印["hello", "do", "you", "know", "how"]
push() 从数组尾部添加一个元素。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.push("news")
console.log(arr)
打印["hello", "do", "you", "know", "how", "many?", "news"]
shift()
把数组的第一个元素从其中删除。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.shift()
console.log(arr)
打印["do", "you", "know", "how", "many?"]
unshift() 从数组第一个元素前添加。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.unshift("news")
console.log(arr)
打印["news", "hello", "do", "you", "know", "how", "many?"]
var arr=['1','2','2','5','3','10','3','10','20','21'];
var a=[];
function array(arr){
for(var i=0;i<arr.length;i++){
if(a.indexOf(arr[i])<0){//在a数组中找不到相同的数时,把arr数组的值插入a数组中。
a.push(arr[i])
}
}
return a;
}
array(arr)
console.log(a)
splice() 方法用于插入、删除或替换数组的元素。
array.splice(index,howmany,item1,.....,itemX)
index 必需。规定从何处添加/删除元素。
该参数是开始插入和(或)删除的数组元素的下标,必须是数字。
howmany必需。规定应该删除多少元素。必须是数字,但可以是 "0"。
如果未规定此参数,则删除从 index 开始到原数组结尾的所有元素。
item1, ..., itemX 可选。要添加到数组的新元素
var arr=["appendChild","removeChild","replaceChild","insertBefore"]
arr.splice(2,0,"haha")
console.log(arr)
第二个填0的话添加进数组
打印["appendChild", "removeChild", "haha", "replaceChild", "insertBefore"]
第二个填1的话添加进数组,然后在这个位置删除一个数。相当于把它替换了。
打印["appendChild",
"removeChild", "haha", "insertBefore"]
第二个填1的话添加进数组,第三个不填就会删除。
打印["appendChild", "removeChild", "insertBefore"]
split()切割成数组的形式
var arr="hello do you know how many?"
var news=arr.split(" ")
console.log(news)
打印的是["hello", "do", "you", "know", "how", "many?"]
join()转换成字符串
var arr=['split','match'];
console.log(avar arr=["hello", "do", "you", "know", "how", "many?"];
arr.push("news")
console.log(arr)rr.join('-'))
没有添加 '-' 的是split,match
打印的是 split-match
push()尾部添加 pop()尾部删除 unshift()头部添加 shift()头部删除
pop()删除数组的最后一个元素。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.pop()
console.log(arr)
打印["hello", "do", "you", "know", "how"]
push() 从数组尾部添加一个元素。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.push("news")
console.log(arr)
打印["hello", "do", "you", "know", "how", "many?", "news"]
shift()
把数组的第一个元素从其中删除。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.shift()
console.log(arr)
打印["do", "you", "know", "how", "many?"]
unshift() 从数组第一个元素前添加。
var arr=["hello", "do", "you", "know", "how", "many?"];
arr.unshift("news")
console.log(arr)
打印["news", "hello", "do", "you", "know", "how", "many?"]
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