Array object in ts Usage in


Array object in TS Usage in

*
length length

let songs:string[]=['red','blue','pink']

console.log(songs.length)

*
push**push()** Method adds one or more elements to the end of the array , And return the new length of the array

3.**forEach()** Method executes the given function once for each element of the array , Will run 5 second , And it can't stop in the middle .

let songs: string[]=['red','green','pink']

songs.forEach(function(item,index){

console.log(' Index is ',index,‘ Element is ’,item)

})

notes ：forEach The parameter of the method is a function , This function is also called a callback function

1.item Represents each element in the array , amount to songs[i]

2.index Represents an index , amount to i

The callback function here is as forEach Method arguments passed in , Type annotation should not be specified （ On call forEach Yes, it has been created )

// It is understood as hiding

function forEach(callbackfn: (value:string,index:number)=>void){

}

forEach(function(value,index){})

3.some As long as one of the conditions is met , Will stop the cycle , And according to the return value , Decide whether to stop the cycle （ture, stop it ;false, continue ）

let nums:number[]=[1,2,3,4,5,6]

nums.some(function (num){

if(num>3){

return true

}

return false

})

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