Web Front-endJS TutorialGenerate all permutations and combinations of strings through JavaScript functionsGenerate all permutations and combinations of strings through JavaScript functions
Today I will introduce to you how to generate all permutations and combinations of strings through a JavaScript function. The so-called permutations and combinations are the most basic concepts in combinatorics.
First of all, let me give you a brief introduction to permutations and combinations:
1. Arrangement refers to sorting out a specified number of elements from a given number of elements.
2. Combination refers to taking out only a specified number of elements from a given number of elements, regardless of sorting.
The central problem of permutations and combinations is to study the total number of possible situations in permutations and combinations of specified requirements.
I believe everyone has some understanding of permutations and combinations.
Below we will use javascript code to calculate all permutations and combinations of strings.
The complete code is as follows:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
//编写一个JavaScript函数来生成字符串的所有组合
function substrings(str1)
{
var array1 = [];
for (var x = 0, y=1; x < str1.length; x++,y++)
{
array1[x]=str1.substring(x, y);
}
var combi = [];
var temp= "";
var slent = Math.pow(2, array1.length);
for (var i = 0; i < slent ; i++)
{
temp= "";
for (var j=0;j<array1.length;j++) {
if ((i & Math.pow(2,j))){
temp += array1[j];
}
}
if (temp !== "")
{
combi.push(temp);
}
}
console.log(combi.join("\n"));
}
substrings("dog");
</script>
</body>
</html>Here we arrange and combine a sample string dog, and view the generated results as follows:
In the above code, we used several key methods, as follows:
1, pow() method: used to calculate y times of x Power, the syntax is "Math.pow(x,y)".
2, push()Method: You can add one or more elements to the end of the array and return the new length. The syntax is "array.push(item1, item2 , ..., itemX)".
3. join() method: used to put all the elements in the array into a string. The elements are separated by the specified delimiter. The syntax is " arrayObject.join(separator)".
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