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November 11, 2017 16:36
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implementing some lodash functions
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| // modification version | |
| function once(f) { | |
| let hasRun = false; | |
| let result; | |
| return () => { | |
| if (!hasRun) { | |
| result = f(); | |
| hasRun = true; | |
| } | |
| return result; | |
| }; | |
| } | |
| function init() { | |
| console.log('initializing'); | |
| } | |
| const t = once(init); | |
| t(); | |
| t(); | |
| function rearg(f, argumentIndeces) { | |
| return (...args) => { | |
| const reordered = _.map(argumentIndeces, index => _.nth(args, index)); | |
| return f(...reordered); | |
| }; | |
| } | |
| function orig(a, b, c) { | |
| return [a, b, c]; | |
| } | |
| const rearged = rearg(orig, [2, 0, 1]); | |
| console.log(rearged('b', 'c', 'a')); | |
| function after(n, f) { | |
| let runs = n; | |
| return () => { | |
| if (runs <= 1) { | |
| return f(); | |
| } else { | |
| runs -= 1; | |
| } | |
| }; | |
| } |
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