A summary of the string’s replace method

grammar

str.replace(regexp|substr, newSubStr|function)

Parameter description:

1. regexp (pattern)

A RegExp object or its literal. What the re matches is replaced by the return value of the second argument.

2. substr (pattern)

A string to be replaced by newSubStr. It is treated as an entire string, not as a regular expression. Only the first match is replaced.

3. newSubStr (replacement)

A string used to replace the matching part of the first argument in the original string. Special variable names can be interpolated into the string. See using strings as arguments below.

4. function (replacement)

A function that creates a new substring whose return value replaces the result of the first argument. Refer to specifying a function as an argument below.

Return value: Returns a new string that partially or completely matches the replacement pattern.

Description: This method does not change the string from which it was called, but simply returns a new, replaced string. When performing global search and replace, the regular expression must contain the G flag.

Use a string as an argument

Substitution strings can insert the following special variable names:

Specify a function as an argument

You can specify a function as the second argument. In this case, the function is executed when the match is executed. Function returns the value as the replacement string. (Note: The special substitution argument mentioned above cannot be used here.) Also note that if the first argument is a regular expression and it is a global match pattern, the method will be called multiple times, with each match being called.

The instance

Example 1 simple string substitution:

    let reg = /sentence/;
    let str = 'This is a simple centence.';
    str = str.replace('centence'.'sentence'); // Plain string substitution
    console.log(str); // This is a simple sentence.
    
    str = str.replace(reg, 'example');
    console.log(str); // This is a simple example.
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Example 2 The code provided in this example ensures that the matching string uppercase characters are correct:

    let text = "javascript Tutorial";
    let txt = text.replace(/javascript/i."JavaScript");
    console.log(txt); // Javascript Tutorial
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Example 3 In this example, we will convert “Doe, John” to the form “John Doe” :

    let n = "Doe , John";
    let nn = n.replace(/(\w+)\s*,\s*(\w+)/."$2 $1");
    console.log(nn); // John Doe
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Example 4 All double quotes replace single numbers:

    let e = '"aa", "ab" , "bb"';
    let ee = e.replace(/"([^"]*)"/g."' $1 '");
    console.log(ee); // 'aa', 'ab', 'bb'
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Example 5 using a string as an argument:

    var st = 'abcdefg';
    var reg1 = /(c)de/g;
    st = st.replace(reg1, '$$d'); // The c wrapped in parentheses is replaced by $, and then the entire matching CDE is replaced
    console.log(st); // ab$dfg
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Example 6 You can perform the following operations to capitalize the first letter of a word in a string

Method 1:

    let str = 'hello world 000 ___',
        reg = /(\w)(\w*)/g;
    let res = str.replace(reg, function (match, p1, p2, offset, str) {
        console.log('match:', match, 'p1:', p1, 'p2:', p2, 'offset:', offset, 'str:', str);
        return p1.toUpperCase() + p2;
    });
    console.log('res:', res);
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The printed values are as follows:

match: hello p1: h p2: ello offset: 0 str: hello world 000 ___
match: world p1: w p2: orld offset: 6 str: hello world 000 ___
match: 000 p1: 0 p2: 00 offset: 12 str: hello world 000 ___
Vmatch: ___ p1: _ p2: __ offset: 16 str: hello world 000 ___
res: Hello World 000 ___
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Method 2:

    let s = 'aaa bbb ccc 000 ___';
    let ss = s.replace(/\b\w+\b/g.function (word) {
        return word.substring(0.1).toUpperCase() + word.substring(1);
    });
    console.log(ss); // Aaa Bbb Ccc 000 ___
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Example 7 Mask the mobile phone number

    // Suppose we have a cell phone number
    let tel = '13194099515',
	r = ' ',
	tmp = '* * * *';
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Method 1:

    r = tel.replace(/\d{4}(? =\d{4}$)/g, tmp); // The first argument is the re (re represents the four digits before the four digits at the end of the match)
    console.log(r); * * * * 9515 / / 131
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Method 2:

    r = tel.replace(/(\d{3})(\d{4})/g.'$1' + tmp); // The first argument is re
    console.log(r); * * * * 9515 / / 131
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Method 3:

    r = tel.replace(tel.slice(3, -4), tmp); // The first argument is a string
    console.log(r); * * * * 9515 / / 131
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Method 4:

    r = tel.replace(/(\d{3})(\d{4})(\d{4})/g.function(match, p1, p2, p3) {
	return p1 + tmp + p3;
    });
    console.log(r); * * * * 9515 / / 131
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Mask Phone number reference:

In the string the replace method (www.cnblogs.com/idiv/p/8442.)