EN
TypeScript - pad left number in string with zeros or spaces to get determined length
3 points
In TypeScript, it is possible to pad left a number with any character in the following ways.
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const padLeft = (number: number, length: number, character: string = '0'): string => {2
let result = String(number);3
for (let i = result.length; i < length; ++i) {4
result = character + result;5
}6
return result;7
};8
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// Usage example:11
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console.log(padLeft(123, 2)); // 12313
console.log(padLeft(123, 4)); // 012314
console.log(padLeft(123, 6)); // 00012315
console.log(padLeft(123, 6, '*')); // ***12316
console.log(padLeft(123, 6, ' ')); // 123ECMAScript 2017 introduced a function that pads numbers.
Simple steps:
1. install ts-polyfill package:
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npm install ts-polyfill2. inside tsconfig.json add es2017.string to the lib.
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{2
"version" : "3.0.3",3
"compilerOptions" : {4
"target": "ES6",5
//...6
"lib": ["es2017.string", /*...*/]7
//...8
},9
"include": [10
"./**/*.ts"11
]12
}3. Run the example
The example below was executed under Node.js:
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// https://github.com/ryanelian/ts-polyfill2
// https://developer.mozilla.org/en-US/docs/Web/TypeScript/Reference/Global_Objects/String/padStart3
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import 'ts-polyfill/lib/es2017-string';5
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const text = '123';7
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console.log(text.padStart(2));9
console.log(text.padStart(4));10
console.log(text.padStart(6));11
console.log(text.padStart(6, '0'));12
console.log(text.padStart(6, '*'));Warning: under Node.js do not forget to add
console.log()declarations.
Output:
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1232
1233
1234
0001235
***123