Detailed explanation of three methods of JS interception string

JS provides three methods for intercepting strings: slice() , substring() and substr() , which can accept one or two parameters:

var stmp = "rcinn.cn";

Using a parameter

alert(stmp.slice(3)); //Start from the 4th character and intercept to the last character; return "nn.cn"

alert(stmp.substring(3)); //Start from the 4th character and intercept to the last character; return "nn.cn"

Using two parameters

alert(stmp.slice(1,5)) //Starting from the 2nd character, to the 5th character; returns "cinn"

alert(stmp.substring(1,5)); //Starting from the 2nd character, to the 5th character; returns "cinn"

If only one parameter is used and it is 0, then the entire parameter is returned.

alert(stmp.slice(0)); //Return the entire string

alert(stmp.substring(0)); //Return the entire string

Returns the first character

alert(stmp.slice(0,1));//return "r"

alert(stmp.substring(0,1));//return "r"

//In the above example, we can see that the usage of slice() and substring() is the same, and the returned value is the same, but參數為負數時，他們的返回值卻不一樣. See the following example

alert(stmp.slice(2,-5));//return "i"

alert(stmp.substring(2,-5));//return "rc"

//From the above two examples, we can see that slice(2,-5) is actually slice(2,3), negative 5 plus the string length 8 is converted to positive 3 (if the first digit is equal to or greater than the second digit (slice()注意：這里第二位數字如果是負數是加完字符串長度后的數字，而不是顯示的數字例：length=11,(7,-6),-6+11=5第二位小于第一位) , then an empty string is returned); and substring(2,-5) is actually substring(2,0), negative numbers are converted to 0, and substring always takes the smaller number as the starting position.

alert(stmp.substring(1,5)) //Starting from the 2nd character to the 5th character; returns "cinn"

alert(stmp.substr(1,5)); //Starting from the second character, intercept 5 characters; return "cinn."

var phone = 15989012100;

phone.slice(-6) takes the last 6 digits (the second parameter does not need to be written as 0), and returns '012100 ';

phone.slice(-6, -4) takes the last 4 digits to the last 6 digits, (-6+11, -4+11) = (5, 7);

// Compare the date size. When the date is smaller than 1 every month, var nowdate = new Date();
item = 2016-7-16;
temp = item.split('-');
if (temp[0] != curYear || temp[1] != curMonth) {
    return;
}
temp[1] = parseInt(temp[1]) + 1;
date = new Date(temp.join('-'));
if(date>=nowdate){
Execute A;
}else{
Execute B;
}

Replace the letters after the specified string

var abc = 'adadada=ss';
var j = abc.substring(abc.indexOf('=')+1,abc.length);
var dsd = abc.replace(j,'haha'); --> dsd = 'adadada=haha'

The above are three methods of JS string interception introduced by the editor. I hope it will be helpful to everyone. I would also like to thank everyone for their support of the 123WORDPRESS.COM website!