JS operation tips, the work is simple
1. Add 0 operation
Scenario: page month and day display, need to use 0 or other character placeholder.
var number = 11;
('0' + number).slice(-2);
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2, thousandths division
Scenario: Page display amount, digit division.
Const AmountSlite = (value) => {const regExp = /(\d{1,3})(? =(\d{3})+(? : $| \.) )/g; const ret = (value +' ').replace(regExp, '$1');
return ret;
};
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3. Check the digits from 0 to 100 with a maximum of two valid digits
Scenario: Percentage check, input box digit check
Var/reg = ^ \ d \. ([1-9] {1, 2} | [0-9] [1-9]) $| ^ [0-9] \ d {0, 1} (\. \ d {1, 2}) {0, 1} $| ^ 100 (\. 0} {1, 2) {0, 1} $/; Var reg1 = /^[1-9](\d+)? (\ \ d {1, 2})? $) | (^ \ \ d \ d {1, 2} $/ / / is greater than or equal to 0, retain two decimal places var reg2 = / ^ (0 | \ [1-9] d *) (\ s $| | \ \ d {1, 2} \ b) /Copy the code
4. Swap two numbers quickly
Scenario: Algorithmic sort swaps two values
let x = 1;
let y = 2;
[x ,y] = [y, x];
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5. Get the last day of the month
Scenario: depending on the month, or the last day of the month
new Date('2020'.'1', 0).getDate();
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6. Use the keyword void
Scenario: Using the void operator ensures that you get a true undefined. Also used for minimization purposes.
console.log(1); // 1
console.log(void 1);
let obj = {
m: 1
};
console.log(void obj.m);
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7, arbitrary type judgment
Scenario: Get variable types
const type = data => Object.prototype.toString.call(data).replace(/^\[object (.+)\]$/, '$1').toLowerCase();
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Js evokes wechat
Scenario: H5 operates wechat
window.location.href="weixin://"; / / H5 operating WeChat: http://www.xiaoshu168.com/jquery/172.htmlCopy the code9. Filter the falsy value in the array
Scenario: Filter the array for falsy values you don’t want
const arr = [0, 1, '0'.'1', +0, -0, undefined, null, 'undefined'.'null'.' '.'snail'.true.false, NaN, 'NaN'];
arr.filter(Boolean);
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