Array of chrome native methods_javascript skills-JS Tutorial-php.cn

Array of chrome native methods_javascript skills

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Release： 2016-05-16 17:58:57

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Let’s take a look at some array methods implemented in chrome/15
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concat: This is easy to say. The only thing to note is that concat is not modified in place. It refers to returning the result after the link. Another point is to expand the first layer array
join :Connect array
pop: Pop operation, note that this also modifies the original array in place
push: Push operation, note that this also modifies the original array in place
reverse: Reverse array, note that this also modifies the original array in place Modify the original array
shift: Dequeue operation, note that this also modifies the original array in place
unshift: Insert an item at the head of the array, and move the following items back
slice: Intercept a part of the array, and insert one A common operation is to use this method to convert a class array into a real array
splice: Modify the array, which can be used to insert new items. Note that this also modifies the original array in place.
sort: Array sorting. Note that this is also Modify the original array
toLocaleString: Return the local string form of the array, usually using commas
toString: Return the string form of the array, usually use commas
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isArray: Determine whether a variable is an array. Note that this is static Method, calling form Array.isArray()
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every: Determine whether the items in an array all meet the conditions. If they all meet the conditions, return true, otherwise return false.
some: This can be linked to every, and every requires all to be true. It is true at the end. As long as one item of some is true, the return value is true
filter: Filter out qualified items from the array according to the given conditions, and then return them as a new array, otherwise return null
forEach: Perform the given operation once for each item in the array
indexOf: Returns the first position of the given item in the array (starting from the 0 index)
lastIndexOf: The opposite of indexOf
map: Perform the given operation once for each item in the array and return the modified array
reduce:reduce(func,init) func is a binary function, and func is applied to the elements of the seq sequence, each time carrying a pair (the previous result and the next element of the sequence), successively apply the existing result and the next value to the subsequent result obtained, and finally reduce our sequence to a single return value.
reduceRight: Implementation of reduce from right to left
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When we implement our own small library or some tools, we can also expand it slightly

Copy code The code is as follows:

 
Object.prototype.extend = function(src){ 
for(var i in src){ 
this[i] = src[i] ; 
} 
} 
Array.extend({ 
toArray : function(arrayLike){ 
try{ 
return [].slice.call(arrayLike); 
} catch(ex){ 
var ret = []; 
for(var i = 0,len = arrayLike.length ; i < len ; i ){ 
ret.push(arrayLike[i]) ; 
} 
} 
}, 
isArray : (Array.isArray)?Array.isArray:function(ele){ 
return ele.constructor == Array; 
} 
}) 
Array.prototype.extend((function(){ 
var each = Array.prototype.forEach || function(fn,obj){ 
for(var i = 0,len = this.length ; i < len ; i ){ 
fn.call(obj,this[i]); 
} 
}; 
var filter = Array.prototype.filter || function (fn,obj){ 
var result = []; 
for(var i = 0,len = this.length ; i < len ; i ){ 
if(fn.call(obj, this[i])){ 
result.push(this[i]); 
} 
} 
return result; 
}; 
var every = Array.prototype.every || function(fn,obj){ 
for(var i = 0,len = this.length ; i < len ; i ){ 
if(!fn.call(obj,this[i]) ){ 
return false; 
} 
} 
return true; 
}; 
var some = Array.prototype.some || function(fn,obj){ 
 for(var i = 0,len = this.length ; i < len ; i ){ 
if(fn.call(obj,this[i])){ 
return true; 
} 
} 
return false; 
}; 
var indexOf = Array.prototype.indexOf || function(dest){ 
for(var i = 0; i < this.length ;i ){ 
if(dest == this[i]){ 
return i; 
} 
} 
return -1; 
}; 
var map = Array. prototype.map || function(fn,obj){ 
var result = []; 
for(var i = 0,len = this.length ; i < len ; i ){ 
result. push(fn.call(obj,this[i])); 
} 
return result; 
}; 
var reduce =Array.prototype.reduce || function(fn,init){ 
var result = init || this[0]; 
for(var i = 0; i < this.length; i ){ 
result = fn(result,this[i]); 
} 
return result; 
} 
return { 
map : map, 
each : each, 
some : some, 
every : every, 
filter : filter, 
indexOf: indexOf, 
reduce : reduce 
} 
})()) 

The following is a small example to set the content for the li under the specified ul:

Copy the code The code is as follows: